Question 1

A 76-year-old woman who has resided in a nursing home for two years is seen, along with her family, to discuss her medical plans. She has chronic kidney disease with an estimated glomerular filtration rate (eGFR) of 7 ml/min/1.73 m². Her other medical problems include type 2 diabetes mellitus, chronic congestive heart failure, moderate cognitive impairment, recurrent falls, a previous hip fracture, and impaired vision. She gets up in a chair for approximately 1 hour per day. She needs help with all activities of daily living except for feeding herself. She relates that she is comfortable and voices no complaints. On examination, her BMI is 19 kg/m² and she appears frail. There is 2+ pitting pedal edema bilaterally, bibasilar fine inspiratory crackles, and a stage 2 sacral pressure ulcer. An ultrasound of her kidneys at the time of admission to the nursing home revealed no obstruction. Which of the following is the best management plan?

Accepted Answer

Renal replacement therapy extends and improves the quality of life for most individuals, but it can induce or prolong suffering in others. Frail individuals with significant co-morbidity, such as this patient, may be in the latter group. One study of nursing home residents (mean age 73 and average eGFR of 10.7 ml/min) started on hemodialysis found a 58% 1-year mortality. Furthermore, these patients had limited functional status before dialysis and the health of 87% declined further after dialysis. Other studies report that unacceptable quality of life is a common reason for discontinuing chronic dialysis. Palliative/supportive care is the most appropriate option for this patient since there is a low likelihood of either hemo- or peritoneal dialysis significantly increasing quality of life (Choices A & E). (Choice B) Given that this patient is already has end-stage renal disease with a low GFR, further evaluation for reversible causes of renal failure would be low yield. (Choice C) A low protein diet, which may occasionally relieve some symptoms of uremia, is not appropriate for this frail undernourished patient. Educational objective: The risk/benefit of renal replacement therapy should be assessed in older patients and may not be indicated for selected individuals with significant co-morbidity, especially in nursing home residents. __________ References: Functional status of elderly adults before and after initiation of dialysis. (http://www.ncbi.nlm.nih.gov/pubmed/19828531) Differences between physicians in the likelihood of referral and acceptance of elderly patients for dialysis-influence of age and comorbidity. (http://www.ncbi.nlm.nih.gov/pubmed/17595178)

Question 2

A 43-year-old African-American man with known HIV is evaluated for edema.  A diagnosis of HIV was established five years ago and HAART therapy initiated, but he has been non-compliant due to side effects.  He began experiencing leg edema 3 months ago that has progressively increased in severity. 
His temperature is 36.6 C (97.9 F), blood pressure is 130/82 mm Hg, and pulse is 84/min.  Cardiac, pulmonary, and abdominal examinations are unremarkable.  He has 3+ ankle edema that extends to the knees and 1+ presacral edema.
His laboratory studies are shown below.

Which of the following would you expect to see on kidney biopsy?

Accepted Answer

This patient's clinical presentation is most suggestive of HIV-associated nephropathy, which is focal segmental glomerulosclerosis (FSGS) of the collapsing histologic type. FSGS mainly occurs in African-Americans, HIV patients with low CD4 counts and high viral loads, and in patients exposed to toxins such as heroin. FSGS in HIV-infected individuals is associated with large echogenic kidneys on ultrasound, few red or white blood cells on urinalysis, heavy proteinuria, and hypoalbuminemia. Surprisingly, hypertension is not seen despite the high incidence of hypertension seen in African Americans. In patients with well-controlled HIV due to HAART, FSGS continues to occur, but the clinical course is more indolent - normal sized kidneys, less proteinuria and a slow decline in glomerular filtration rate. The progression of disease can be decreased with HAART therapy, ACE inhibitors, or angiotensin receptor blockers to reduce proteinuria, and possibly steroids in some cases. (Choice B) IgA-associated glomerulonephritis can occur in HIV patients, but the lack of red blood cells and red blood cell casts on urinalysis makes this diagnosis less likely. IgA-associated glomerulonephritis usually does not present with this degree of proteinuria. (Choice C) Membranous nephropathy due to hepatitis B or C and syphilis can occur in the context of HIV, but hypertension and hematuria are commonly seen with membranous nephropathy. (Choice D) Minimal change disease typically presents with explosive-onset nephrotic range proteinuria, hyperlipidemia, and hypoalbuminemia. Also, minimal change disease is not seen as often in HIV patients. (Choice E) Interstitial nephritis is commonly seen in patients with HIV. While acute interstitial nephritis can be associated with heavy proteinuria, chronic interstitial nephritis usually does not present with heavy proteinuria and often has white blood cells and cellular casts on urinalysis. Educational objective: Focal segmental glomerulosclerosis (FSGS) is the most characteristic renal lesion seen in African-Americans with HIV. FSGS in HIV-infected individuals is associated with large echogenic kidneys on ultrasound, few red or white blood cells on urinalysis, heavy proteinuria, and hypoalbuminemia. Surprisingly, hypertension is not seen despite the high incidence of hypertension seen in African Americans. __________ References: Pathogenesis and treatment of HIV-associated renal diseases: lessons from clinical and animal studies, molecular pathologic correlations, and genetic investigations. (http://www.ncbi.nlm.nih.gov/pubmed/12899589) Pathologic classification of focal segmental glomerulosclerosis. (http://www.ncbi.nlm.nih.gov/pubmed/12704572)

Question 3

A 75-year-old man comes to the office for hypertension follow-up.  The patient has been taking chlorthalidone since being diagnosed with hypertension 15 years ago, and he was started on metoprolol 4 years ago after he had a non-ST elevation myocardial infarction.  Over the last 2 years, his blood pressure measurements have ranged from 160/80 mm Hg to 180/100 mm Hg, and amlodipine was added to his medical regimen 6 months ago.  The patient has had no chest pain, dyspnea, palpitation, headache, or subjective neurological deficits.  His medical history includes hyperlipidemia and peripheral vascular disease, and other medications are aspirin and atorvastatin.  The patient is a former smoker with a 30-pack-year history and does not use alcohol or illicit drugs.
Today, blood pressure is 165/86 mm Hg and pulse is 68/min.  Physical examination is notable for an abdominal bruit.
Serum creatinine is 1.2 mg/dL, and duplex Doppler ultrasonography reveals >60% stenosis of bilateral renal arteries.
Which of the following is the most appropriate next step in management of this patient?

Accepted Answer

This elderly patient who has uncontrolled hypertension despite multidrug therapy and is found to have high-grade bilateral renal artery stenosis should be treated with an ACE inhibitor. Bilateral renal ischemia (caused by limited blood supply to the poststenotic kidney) induces the activation of the renin-angiotensin-aldosterone system (RAAS), which leads to sodium retention and volume expansion. As the RAAS is involved, a combination of a diuretic with an ACE inhibitor or angiotensin receptor blocker (ARB) is the preferred initial treatment. ACE inhibitors have been shown to decrease mortality, rate of myocardial infarction, progression to end-stage renal disease, and stroke and are equally as effective as angioplasty in most patients. Patients with bilateral renal artery stenosis are at increased risk of development of acute kidney injury; however, ACE inhibitors and ARBs are no longer thought to be contraindicated in this population as most patients only experience a small decline in glomerular filtration rate. More marked declines are usually reversible with dose reduction or elimination of the diuretic; patients should be monitored closely while on these medications. Other antihypertensive agents and statins, as well as antiplatelet therapy should be added when appropriate along with lifestyle changes. Patients who fail optimal medical therapy (eg, refractory hypertension, inability to tolerate medications, progressive renal insufficiency) or those with recurrent flash pulmonary edema or heart failure should undergo revascularization with stenting (Choice D). (Choice B) Although invasive renal angiography is considered the gold standard for diagnosis of renal artery stenosis, less invasive imaging (eg, ultrasound, MRI, CT scan) is preferred due to the risk of complications associated with angiography (eg, contrast load, cholesterol embolization). (Choice C) Plasma renin activity (PRA) measurements are useful to distinguish between primary and secondary hyperaldosteronism in patients with refractory hypertension. PRA is expected to be low in patients with primary hyperaldosteronism and elevated in patients with renovascular hypertension. However, up to 50% of patients with renovascular hypertension do not have an elevated PRA, and levels are suppressed by antihypertensives, high sodium diet, and bilateral renal artery disease, limiting the practical use of PRA measurement. (Choice E) Surgery is recommended for patients who have early primary branching of the main renal artery or multiple small renal arteries, have failed prior stenting, or require aortic reconstruction for other reasons (eg, aneurysm, aorto-iliac disease). Educational objective: Patients with bilateral renal artery stenosis should first be treated with medical therapy (eg, a diuretic and either ACE inhibitor or angiotensin receptor blocker) as it is as efficacious as angioplasty or surgery. Patients who fail optimal medical therapy (eg, progressive renal insufficiency) or those with recurrent flash pulmonary edema or heart failure should be considered for angioplasty. __________ References: Revascularization versus medical therapy for renal-artery stenosis. (http://www.ncbi.nlm.nih.gov/pubmed/19907042) Renal artery stenosis: a common, treatable cause of renal failure? (http://www.ncbi.nlm.nih.gov/pubmed/11160787)

Question 4

An 80-year-old man comes to the physician because of a skin rash on his legs.  He also complains of mild fatigue and a poor energy level.  He denies chest pain/pressure, orthopnea, or dyspnea with exertion.  Two weeks ago, he underwent coronary arteriography for unstable angina and had a stent placed in his right coronary artery.  His subsequent hospital course was uncomplicated.  His other medical problems include hyperlipidemia, type 2 diabetes mellitus, hypertension, and mild cognitive impairment.  His current medications include low-dose aspirin, benazepril, atenolol, clopidogrel, hydrochlorothiazide, rosuvastatin, and glipizide.  Clopidogrel was added after the stent placement.
His blood pressure is 144/82 mm Hg and pulse is 72/min.  His lungs are clear on auscultation.  There is a mottled, lace-like, purplish discoloration of both lower extremities from the mid-thigh downward.  His pulses are 1+ bilaterally over the distal lower extremities.
Laboratory results are as follows:

Which of the following is the most likely diagnosis?

Accepted Answer

11ec193a_98fe_9027_853d_0362e303e81b_MD0002_00 This patient's presentation is consistent with renal atheroembolic disease (cholesterol crystal emboli), which usually occurs after manipulation of the aorta or other large arteries in patients with atherosclerotic disease. The existing atherosclerotic plaque usually breaks off and embolizes to multiple small arteries leading to tissue and/or organ ischemia. Diagnosis is suggested by subacute onset of acute kidney injury (AKI), particularly with extrarenal embolic disease such as livedo reticularis and cyanotic toes. A skin or kidney biopsy may be necessary in some patients with an unclear diagnosis. Treatment is largely supportive and directed against secondary prevention of cardiovascular disease with aspirin, statins, blood pressure control, and smoking cessation. (Choice A) Acute interstitial nephritis usually causes fever, rash, and eosinophilia. However, it is usually not associated with extra-renal disease such as livedo reticularis or cyanotic toes. (Choice B) Acute kidney injury due to angiotensin converting enzyme inhibitors usually occurs soon after starting the drug and is not associated with an abnormal urinary sediment, as seen in this patient. (Choice D) Pre-renal azotemia usually presents with a spot urinary sodium concentration < 20 mEq/L and normal urinary sediment. This patient's urinary sodium of 38 mEq/L and abnormal urine sediment makes this less likely. (Choice E) Although this patient is at risk, radiocontrast AKI usually resolves within two weeks and is not associated with eosinophilia and livedo reticularis. Educational objective: Atheroembolic disease usually presents with acute kidney injury after arteriography involving the aorta, and is associated with livedo reticularis and a cyanotic or gangrenous toe. __________ References: The challenge of diagnosing atheroembolic renal disease. Clinical features and prognostic factors. (http://www.ncbi.nlm.nih.gov/pubmed/17606842) Cholesterol embolization: A review of 22 cases in the English literature. (http://www.ncbi.nlm.nih.gov/pubmed/3310742)

Question 5

A 68-year-old man with chronic kidney disease secondary to diabetic nephropathy and hypertension comes to the office for a follow-up visit. The patient has had mild fatigue but no anorexia, nausea, vomiting, chest pain, or shortness of breath. Medical history includes hyperlipidemia, coronary artery disease, and hand osteoarthritis that limits manual dexterity. The patient lives alone and has occasional help from an aide. He is compliant with medications and recommended dietary restrictions. Physical examination reveals clear lungs, no heart murmur, and trace pedal edema. Laboratory results show hemoglobin 11.8 g/dL and serum potassium 4.9 mEq/L. Estimated glomerular filtration rate (eGFR) is 19 mL/min/1.73 m², which was 26 mL/min/1.73 m² a year ago. After a thorough discussion, the patient is interested in renal replacement therapy. Which of the following is the most appropriate next step in management?

Accepted Answer

Patients with advanced chronic kidney disease should be referred to a nephrologist to discuss preparations for renal replacement therapy. Studies have shown similar survival outcomes among patients started on dialysis early (glomerular filtration rate [GFR] of 10-14 mL/min/1.73 m²) versus late (GFR of 5-7 mL/min/1.73 m²). However, waiting until dialysis is emergently required (eg, hyperkalemia, volume overload, uremic symptoms) places patients at high risk for complications (eg, arrhythmias, respiratory failure) and should be avoided (Choice C). ² ² Arteriovenous (AV) fistulas are the preferred vascular access modality for chronic hemodialysis (rather than an AV graft) due to fewer complications and improved longevity (Choice B). However, maturation of a fistula takes up to 3 months. Therefore, if hemodialysis is anticipated, preemptive placement of an AV fistula (typically when GFR is 15-20 mL/min/1.73 m²) is recommended. ² (Choice D) Peritoneal dialysis requires placement of a peritoneal catheter 2 weeks before use (although it can be used immediately if needed). However, peritoneal catheters require significant daily care and are relatively contraindicated in patients unable to perform catheter care, as in this patient who has limited manual dexterity. (Choice E) Emergency dialysis via a central venous catheter should be avoided if possible, as these catheters are associated with relatively high rates of complications (especially infections) and diminished survival. Educational objective: Arteriovenous fistulas are the preferred vascular access modality for chronic hemodialysis. However, maturation of a fistula takes up to 3 months. Therefore, if hemodialysis is anticipated, preemptive placement of an AV fistula is recommended, typically when the glomerular filtration rate is 15-20 mL/min/1.73 m². ² __________

Question 6

A 37-year-old woman is evaluated for generalized weakness. She has been hospitalized twice over the last year with similar complaints and her serum potassium concentration was found to be < 3.0 mEq/L. Her potassium concentration returned to normal with aggressive potassium replacement. She eats a normal diet and denies vomiting, purging, and cathartic or diuretic use. Her blood pressure is within normal limits. Her only medication is an oral contraceptive. Her review of systems is otherwise unremarkable. Her sister suffers from Crohn's disease and her mother has congestive heart failure, diabetes mellitus, and bipolar disorder. Her blood pressure is 112/68 mm Hg and her pulse is 90/min. Her BMI is 22 kg/m². Physical examination is normal. Laboratory studies are shown below: Spot urinary chloride concentrations on two separate occasions were 15 and 65 mEq/L. Which of the following is most likely to establish diagnosis in this patient?

Accepted Answer

This patient presents with unexplained hypokalemia and metabolic alkalosis. The most common causes are vomiting/purging and diuretic use. Surreptitious vomiting or purging can be difficult to diagnose, but it usually presents with significant metabolic alkalosis and a low urinary chloride. This patient also lacks signs of self-induced vomiting such as ulcers on the dorsum of the hand, dental erosions from chronic acid exposure, or puffy cheeks from hypertrophied salivary glands. Diuretics cause a high urine chloride and metabolic alkalosis, but the urine chloride returns to low levels once the drug's effect wears off. As a result, surreptitious diuretic use is often associated with intermittent hypokalemia and variable urinary chloride excretion. In patients without physical signs of self-induced vomiting, a positive urinary screen for diuretics (usually on several occasions) is required to confirm the diagnosis of diuretic abuse. (Choice A) CT angiography of the renal arteries diagnoses renal artery stenosis and fibromuscular dysplasia, which both cause hypertension usually with a urine chloride > 40 mEq/L. This patient's normal blood pressure and variable urinary chloride make this less likely. (Choice B) Colonoscopy would be indicated for gastrointestinal causes of hypokalemia (e.g., diarrhea, surreptitious cathartic use, or a secretory villous adenomas), but those patients usually have metabolic acidosis from bicarbonate loss rather than alkalosis. (Choice C) Elevated plasma aldosterone with suppressed renin suggests hyperaldosteronism, which usually presents with persistent hypokalemia and hypertension. This patient's normal blood pressure and episodic hypokalemia make this less likely. (Choice D) Elevated C-peptide and insulin levels would suggest exogenous oral hypoglycemic agent abuse or insulinoma. Elevated insulin levels with low C-peptide levels suggest exogenous insulin abuse. However, this patient's lack of hypoglycemia makes this less likely. Educational objective: Intermittent hypokalemia with metabolic alkalosis in the absence of vomiting suggests a diagnosis of either surreptitious purging or diuretic use. A variable urinary chloride favors diuretic abuse and can be confirmed with a urinary screen for diuretics. __________ References: The clinical features of covert diuretic use. (http://www.ncbi.nlm.nih.gov/pubmed/7179952)

Question 7

A 36-year-old woman has increasing nausea and headaches 12 hours after a right-sided percutaneous nephrolithotomy for staghorn calculi.  The procedure involved ultrasonic lithotripsy followed by fragment removal using a flexible nephroscope.  The patient spent a prolonged period in recovery and has been drowsy since returning to the ward.  She is receiving intermittent morphine for pain control.  She also received intravenous ceftriaxone after an episode of postoperative low-grade fever.
Other medical conditions include frequent urinary tract infections, gastroesophageal reflux disease, and angioedema.  A month ago, the patient was treated for contact dermatitis from poison ivy with a 10-day course of prednisone.
Temperature is 37.2 C (99 F), blood pressure is 130/90 mm Hg, pulse is 64/min, respirations are 14/min, and oxygen saturation is 96% on room air.  The patient is drowsy but arousable with a short attention span.  Pupils are small but reactive to light and accommodation.  Mucous membranes are moist.  The neck is supple, and cardiovascular and lung examinations are unremarkable.  Abdominal examination reveals diminished bowel sounds.  The patient is able to move all extremities on command, and deep tendon reflexes are symmetric.  The remainder of the examination is normal.
Laboratory results are as follows:
 The patient's preoperative laboratory studies were normal.  Which of the following is the most appropriate next step in management of this patient?

Accepted Answer

11ec193a_98ff_2c69_853d_65d360a7075d_MD0002_00 This patient, who is experiencing nausea, headaches, and drowsiness following lithotripsy, has acute symptomatic hyponatremia, likely related to her recent surgery. Postoperative hyponatremia can develop within hours of surgery due to release of vasopressin related to surgical stress, the use of nonelectrolyte solutions (eg, glycine, sorbitol) for irrigation, or the infusion of hypotonic solutions during surgery. Patients with hyponatremia may be asymptomatic, or they may have mild (eg, headache, nausea, vomiting, confusion) or severe (eg, seizure, obtundation, coma) symptoms. Untreated patients may develop cerebral edema and brain herniation. Management depends on hyponatremia chronicity and associated symptoms: Patients with acute (<24-48 hours) hyponatremia who are symptomatic, such as this patient, should be treated emergently with hypertonic saline while being carefully monitored. The goal is to relieve symptoms and increase the sodium level relatively rapidly (eg, 4-6 mEq/L within the first few hours); the correction rate should not exceed 8 mEq/L in 24 hours.Regardless of hyponatremia chronicity, patients with severe symptoms and those with intracranial pathology (eg, intracranial tumor, recent traumatic brain injury) should also receive hypertonic saline.In patients who do not require hypertonic saline, including most patients with chronic hyponatremia, serum sodium levels should be increased slowly; treatment depends on the underlying disease (eg, fluid restriction in hypervolemic patients, normal saline in hypovolemic patients). Patients with acute (<24-48 hours) hyponatremia who are symptomatic, such as this patient, should be treated emergently with hypertonic saline while being carefully monitored. The goal is to relieve symptoms and increase the sodium level relatively rapidly (eg, 4-6 mEq/L within the first few hours); the correction rate should not exceed 8 mEq/L in 24 hours. Patients with acute (<24-48 hours) hyponatremia who are symptomatic, such as this patient, should be treated emergently with hypertonic saline while being carefully monitored. The goal is to relieve symptoms and increase the sodium level relatively rapidly (eg, 4-6 mEq/L within the first few hours); the correction rate should not exceed 8 mEq/L in 24 hours. Regardless of hyponatremia chronicity, patients with severe symptoms and those with intracranial pathology (eg, intracranial tumor, recent traumatic brain injury) should also receive hypertonic saline. Regardless of hyponatremia chronicity, patients with severe symptoms and those with intracranial pathology (eg, intracranial tumor, recent traumatic brain injury) should also receive hypertonic saline. In patients who do not require hypertonic saline, including most patients with chronic hyponatremia, serum sodium levels should be increased slowly; treatment depends on the underlying disease (eg, fluid restriction in hypervolemic patients, normal saline in hypovolemic patients). In patients who do not require hypertonic saline, including most patients with chronic hyponatremia, serum sodium levels should be increased slowly; treatment depends on the underlying disease (eg, fluid restriction in hypervolemic patients, normal saline in hypovolemic patients). (Choice B) This patient needs relatively rapid correction of hyponatremia with hypertonic saline to prevent further deterioration in mental status; this cannot be achieved with an isotonic solution such as normal saline. In addition, her physical examination findings (eg, moist mucous membranes, lack of hypotension) do not suggest volume depletion. (Choice C) This patient already received ceftriaxone and does not have signs of sepsis (eg, tachycardia, hypotension) to warrant a change in antibiotics or blood cultures. Her mental status changes are more likely due to hyponatremia. (Choice D) The mechanism of the neurological manifestations of postoperative hyponatremia is unclear, but they may be due to effects of the actual irrigant used or, less commonly, to cerebral edema. In this patient, a noncontrast CT scan of the head may show cerebral edema but would not change management and could delay appropriate treatment. (Choice E) Although this patient received corticosteroids in the past, the lack of hypotension and of metabolic abnormalities consistent with adrenal insufficiency (eg, hyperkalemia, significant metabolic acidosis, hypoglycemia) makes an adrenal crisis less likely. Educational objective: Postoperative hyponatremia usually occurs due to surgical stress-related release of vasopressin, use of nonelectrolyte solutions for irrigation, or infusion of hypotonic solutions. Acute, symptomatic hyponatremia should be emergently treated with hypertonic saline. __________ References: The treatment of hyponatremia. (http://www.ncbi.nlm.nih.gov/pubmed/19523575) Postoperative hyponatremia despite near-isotonic saline infusion: a phenomenon of desalination. (http://www.ncbi.nlm.nih.gov/pubmed/8992919) Diagnosis, evaluation, and treatment of hyponatremia: expert panel recommendations. (http://www.ncbi.nlm.nih.gov/pubmed/24074529)

Question 8

A 63-year-old woman with a long history of type 2 diabetes mellitus is being evaluated for a progressive decline in renal function.  She has no new complaints except for occasional tiredness and lower back pain.  Her other medical problems include hypertension, obesity, mild diabetic retinopathy, and peripheral neuropathy.  One year ago, she was evaluated for atypical chest pain and had a negative exercise stress test.  She is a lifetime non-smoker.  Her current medications include insulin, amlodipine, and low-dose aspirin.  She was treated with lisinopril, which has been stopped recently due to renal dysfunction and hyperkalemia.
Her current eGFR is 15 ml/min, potassium is 5.1 mEq/L, and hemoglobin is 10.2 g/dL.
Which of the following would provide the highest survival benefit in this patient?

Accepted Answer

Diabetes mellitus is the most common cause of end-stage renal disease (ESRD) requiring dialysis, and the 5-year survival for these patients on hemodialysis is around 30-40% (> 50% deaths from cardiovascular disease). Studies show diabetics with ESRD receiving kidney transplant had a 5-year survival of 67-77% and better quality of life. As a result, renal transplant should be offered to all eligible diabetics with ESRD. While a living related donor transplant is the best option, cadaveric transplant also offers increased survival in diabetic patients. Improved survival in diabetics following a cadaveric kidney transplant is maximal in younger age groups but is seen in all age groups, including patients > age 70. (Choices B & D) The optimal time to start dialysis is debated. Studies have shown no difference in outcomes between preemptive dialysis (GFR of 10-15 ml/min/1.73m² without symptoms of uremia) and dialysis at either the onset of uremic symptoms or when the glomerular filtration rate is < 10 ml/min/1.73m². (Choice C) Erythropoietin offers symptomatic relief from anemia of renal failure and indirectly improves cardiovascular morbidity and mortality, but renal transplant offers a higher survival benefit. (Choice E) Peritoneal dialysis is an option for maintenance dialysis in diabetics with stable cardiovascular dynamics, no severe vascular disease, or without advanced neuropathy. Survival with chronic peritoneal dialysis is generally comparable to chronic hemodialysis, but is not better than renal transplant. Educational objective: Diabetics with end-stage renal disease (ESRD) treated with either a living related or cadaveric donor kidney transplant (compared to dialysis) have better survival, quality of life, and rehabilitation. Infections are the most common cause of death in the early post-transplant period. __________ References: Comparison of mortality in all patients on dialysis, patients on dialysis awaiting transplantation and recipients of a first cadaveric transplant. (http://www.ncbi.nlm.nih.gov/pubmed/10580071) A randomized, controlled trial of early versus late initiation of dialysis. (http://www.ncbi.nlm.nih.gov/pubmed/20581422)

Question 9

A 45-year-old man is evaluated for recurrent urolithiasis.  He underwent a Roux-en-Y procedure for morbid obesity two years ago.  He passed his first kidney stone one year ago and has passed several since then.  He has lost approximately 15 kg (33 lb) since the surgery and feels well otherwise.  His current medications include lisinopril for hypertension, esomeprazole for gastro-esophageal reflux disease, and a daily multivitamin.  He has no family history of kidney stones.
Which of the following factors is most likely responsible for this patient's kidney stone formation?

Accepted Answer

11ec193a_9902_fcff_853d_6d3f4c50dcfa_MD0002_00 This bariatric surgery patient has recurrent urolithiasis that is likely due to calcium oxalate stones caused by hyperoxaluria and hypocitraturia. Calcium oxalate stones commonly occur in patients with malabsorption due to small bowel disease (e.g., Crohn's disease), bowel resection with intestinal bypass (e.g., bariatric surgery), and cystic fibrosis. Malabsorption causes more intestinal fatty acid binding to calcium, which increases colonic oxalate absorption and renal oxalate excretion. Malabsorption also causes low urinary citrate due to unclear reasons. One possibility is hypokalemia or chronic metabolic acidosis (from malabsorptive diarrhea), leading to increased citrate reabsorption in the renal proximal tubules. Since citrate is an inhibitor of kidney stones, the combined effect of hyperoxaluria and hypocitraturia increases the risk of kidney stones by up to 4% per year. Patients can be treated with a low oxalate diet and exogenous citrate supplementation. (Choice B) Hypercalciuria is most commonly associated with calcium stones seen in primary hyperparathyroidism and chronic metabolic acidosis. However, it is not a significant contributor to malabsorption-associated kidney stone formation. (Choice C) Hyperuricosuria and low urine pH are known risk factors for uric acid stones; however, they are not associated with calcium oxalate stones due to malabsorption. (Choice D) Patients with bowel disorders and significant diarrhea can have low urinary volumes, which by itself is not a significant risk factor for calcium oxalate stones. Low urinary volume can contribute to uric acid and calcium oxalate stones when combined with low urine pH, metabolic acidosis, and hypocitraturia. (Choice E) The Roux-en-Y procedure can lead to decreased absorption of fat-soluble vitamins (e.g., vitamin D), but vitamin D excess (not deficiency) is associated with calcium stones. Educational objective: Recurrent urolithiasis commonly occurs in gastric bypass patients due to hyperoxaluria and hypocitraturia. Treatment involves a low oxalate diet and exogenous citrate supplementation. __________ References: Effect of gastric bypass surgery on kidney stone disease. (http://www.ncbi.nlm.nih.gov/pubmed/19375090) Hyperoxaluria in kidney stone formers treated with modern bariatric surgery. (http://www.ncbi.nlm.nih.gov/pubmed/17222634)

Question 10

A 45-year-old man comes to the emergency department due to shortness of breath.  His symptoms began when he woke up today and have not diminished since.  The patient also reports mild chest pressure but has no cough, fever, wheezing, or chest pain.  He was diagnosed with idiopathic membranous nephropathy 6 months ago during evaluation of anasarca, and cyclophosphamide and prednisone therapy were begun due to persistent heavy proteinuria.  The patient is a lifelong nonsmoker and does not use alcohol or illicit drugs.
Temperature is 37.2 C (99.0 F), blood pressure is 144/84 mm Hg, pulse is 112/min and regular, and respirations are 18/min.  Oxygen saturation is 91% while breathing ambient air.  There is no jugular venous distension.  The lungs are clear on auscultation, and cardiac examination shows no abnormalities with the exception of tachycardia.  The patient has 2+ bilateral, lower extremity pitting edema.  There is no calf tenderness.
Laboratory results are as follows:
 ECG shows sinus tachycardia with nonspecific ST-T changes.
Which of the following conditions is most likely associated with this patient's current symptoms?

Accepted Answer

11ec193a_98fa_4a5a_853d_c5f153aee6e9_MD0002_00 This patient with membranous nephropathy (a nephrotic syndrome) and acute-onset shortness of breath, chest pain, and tachycardia likely has a pulmonary embolism (PE). In patients with nephrotic syndrome, PE is often the presenting manifestation of chronic renal venous thrombosis (RVT). Patients with nephrotic syndrome (urine protein >3.5 g/day, albumin <3 g/dL, edema) have a markedly increased risk of (venous > arterial) thrombosis, with 12%-30% of patients developing PE. The hypercoagulable state is likely due to both urinary loss of antithrombin III and plasminogen and increased levels of fibrinogen with platelet activation. Membranous nephropathy, the most common cause of nephrotic syndrome, carries the highest risk of thrombosis; up to 60% of patients with membranous nephropathy will develop RVT. This risk is particularly high in patients with >10 g/day of urinary protein or <2 g/dL of serum albumin. RVT that develops in membranous nephropathy is typically chronic, asymptomatic, and often not associated with worsening renal function or proteinuria (as opposed to acute RVT, which presents with pain, hematuria, and renal failure). The thrombus can propagate into the inferior vena cava and embolize into the pulmonary vasculature, resulting in PE (often the only manifestation of chronic RVT). Diagnosis of RVT can be made by selective venography, Doppler ultrasound, CT scan, or MRI; however, routine screening in membranous nephropathy is not recommended. Treatment is anticoagulation. (Choice A) Cyclophosphamide pulmonary toxicity typically results in a pneumonitis with symptoms of cough, fatigue, and dyspnea. It would be unlikely to cause acute chest pain, tachycardia, and a troponin elevation. (Choice B) Right coronary artery myocardial infarction causes an inferior wall myocardial infarction, which in turn causes chest pain and dyspnea; however, an ECG would show ST elevations in the inferior leads (II,III, and aVF). If the right ventricle is involved, hypotension and elevated jugular venous pressure will predominate. The troponin elevation is likely due to right heart strain from acute PE. (Choice C) Pericardial effusions can cause shortness of breath and tachycardia; however, patients typically have elevated jugular venous distension, hypotension, and low voltages on ECG. (Choice D) Bilateral renal artery stenosis can cause flash pulmonary edema (Pickering syndrome); however, this typically presents with hypoxia, severe hypertension, and jugular venous distension. Educational objective: Nephrotic syndrome, particularly membranous nephropathy, is associated with a high frequency of thromboembolic events, predominately deep venous and renal venous thrombosis. Renal venous thrombosis is often asymptomatic; pulmonary embolism may be the presenting sign. __________ References: High absolute risks and predictors of venous and arterial thromboembolic events in patients with nephrotic syndrome: results from a large retrospective cohort study. (http://www.ncbi.nlm.nih.gov/pubmed/18158362) Thromboembolic complications in the nephrotic syndrome: pathophysiology and clinical management. (http://www.ncbi.nlm.nih.gov/pubmed/15990160)

Question 11

A 49-year-old alcoholic man is admitted for diarrhea and generalized abdominal pain.  His blood pressure is 134/80 mm Hg, pulse is 90/min, respirations are 16/min, and oxygen saturation is 97% on room air.  He is disheveled and looks chronically ill.  He is oriented to person and place.  His mucous membranes are dry.  His abdomen is soft and mildly tender in the epigastric region.  He has no focal neurologic findings.
An electrocardiogram and chest x-ray is unremarkable.  Stool samples are sent for culture and microscopic examination.
Laboratory results are as follows:

He is given thiamine and a multivitamin intravenously along with three liters of normal saline with 5% dextrose.  He also receives intravenous potassium and magnesium supplementation.  Thirty-six hours after admission, he complains of severe weakness.  His oxygenation has decreased and he appears agitated.
Repeat laboratory results are as follows:

Which of the following is the most likely cause of this patient's new-onset weakness?

Accepted Answer

11ec193a_98fd_3093_853d_257c841881d8_MD0002_00 This chronically malnourished patient likely developed severe hypophosphatemia due to intravenous dextrose. Chronic alcoholics often have hypophosphatemia due to malnutrition, vitamin D deficiency, and diarrhea. When these patients are hospitalized, refeeding or hydration with glucose-containing fluids stimulates insulin release and drives phosphorus into cells. The phosphorus can drop to severe levels (< 1.0 mg/dL) 12-36 hours later, which further depletes ATP and causes symptoms (e.g., decreased diaphragmatic strength, cardiac function, and neurologic function). Alcohol can also cause decreased renal phosphate absorption in the proximal tubules and further worsen hypophosphatemia. Patients with phosphorus < 2.0 mg/dL may be treated with oral phosphates, while levels < 1.0 mg/dL require intravenous phosphate. However, dextrose-containing fluids should not be given to patients with hypophosphatemia at presentation (such as this patient) unless there is a clear indication for these fluids (e.g., hypoglycemia). (Choice A) Alcohol withdrawal may present with agitation, but usually presents with tachycardia, hypertension, and eventual delirium. In addition, this patient's generalized weakness makes alcohol withdrawal less likely. (Choice B) Hypomagnesemia is usually associated with hypokalemia, which is consistent with this patient's initial laboratory findings. Since magnesium repletion restores potassium to normal levels, this patient's repeat normal potassium level makes hypomagnesemia unlikely. (Choice D) Rhabdomyolysis can occur in alcoholics with severe hypophosphatemia who receive hyperalimentation without phosphate repletion, usually within the first 72 hours. However, these patients tend to have more biochemical abnormalities (e.g., elevated CK) and are usually not this symptomatic. (Choice E) Wernicke's encephalopathy typically presents with acute encephalopathy, oculomotor defects, and gait ataxia. This patient's normal neurological examination makes this less likely. Educational objective: Refeeding or giving dextrose-containing fluids to nutritionally depleted individuals (e.g., alcoholics) can lead to severe hypophosphatemia and resultant multi-organ dysfunction. __________ References: Refeeding syndrome and hypophosphatemia. (http://www.ncbi.nlm.nih.gov/pubmed/15888903) Severe hypophosphatemia: pathophysiologic implications, clinical presentation and treatment. (http://www.ncbi.nlm.nih.gov/pubmed/10670405) Renal tubular dysfunction in chronic alcoholism-effects of abstinence. (http://www.ncbi.nlm.nih.gov/pubmed/8247056)

Question 12

A 63-year-old man comes to the physician for a periodic health evaluation.  He reports nocturia once or twice per night, and he has noticed a decrease in the size and force of his urinary stream over the past six months.  These symptoms mildly affect his quality of life.  There is no additional past medical or surgical history and review of symptoms is otherwise unremarkable.  His father suffered from benign prostatic hyperplasia and underwent prostate surgery.  His mother passed away from breast cancer at the age of 74.
On examination, he appears healthy.  His blood pressure is 128/82 mm Hg and pulse is 72/min.  General physical examination is within normal limits.  On digital rectal examination, his prostate is mildly enlarged.  There is a firm 1 cm nodule in the right lateral lobe of the prostate.
Laboratory results are as follows:

Which of the following is the best next step in this patient's management?

Accepted Answer

11ec193a_9903_7231_853d_4f3bd5916075_MD0002_00 Digital rectal examination can detect focal prostatic abnormalities (nodule or significant asymmetry) in 2-3% of men > age 50; however, its positive predictive value for prostate cancer ranges from 5-30%. A significant number of men with prostate cancer have PSA values < 4.0 ng/mL, and a small but significant percentage have values < 2.0 ng/mL. Current guidelines (shown in the above table) recommend transrectal ultrasound (TRUS) guided prostate biopsy for all men with prostatic nodules, independent of the PSA value or symptoms (Choices B and C). Transrectal ultrasound is usually preformed in the urologist's office with antibiotic prophylaxis, and it can assess prostate volume in addition to improving biopsy accuracy. However, repeat biopsy may be indicated in many patients. (Choice A) Endorectal coil MRI involves placing an endorectal probe to better visualize seminal vesical involvement or extraprostatic extension in patients with localized prostate cancer. It is typically used in conjunction with TRUS biopsy for staging the extent of known prostate cancer, but not for the initial investigation of a prostate nodule. (Choice E) Tamsulosin may improve the mild signs and symptoms of benign prostatic hyperplasia seen in this patient, but the management of this patient's prostate nodule takes priority. Additionally, even without pharmacotherapy, many patients with mild BPH experience improvement or stabilization of symptoms. Educational objective: Prostatic nodules found on digital rectal examination should be promptly evaluated by transrectal ultrasound (TRUS) guided prostatic biopsy, regardless of the PSA level. __________ References: Transrectal sonography in prostate evaluation. (http://www.ncbi.nlm.nih.gov/pubmed/17030220) Indications and timing for prostate biopsy, diagnosis of early stage prostate cancer and its definitive treatment: a clinical conundrum in the PSA era (http://www.ncbi.nlm.nih.gov/pubmed/19282170) Early detection of prostate cancer. Part I. Prior probability and effectiveness of tests. (http://www.ncbi.nlm.nih.gov/pubmed/9054286)

Question 13

A 40-year-old woman comes to the office for follow-up.  She received a living-related donor kidney transplant a year ago for membranoproliferative glomerulonephritis.  The patient feels well and has been consistent with follow-up and medications.  Other medical issues include hypertension and diet-controlled type 2 diabetes mellitus.  Current medications include tacrolimus, prednisone, mycophenolate mofetil, lisinopril, and amlodipine, as well as fluconazole for recurrent vaginal candidiasis.
Temperature is 36.9 C (98.4 F), blood pressure is 152/100 mm Hg, and pulse is 82/min.  Physical examination reveals mild cushingoid features.  The abdomen is soft with no graft tenderness.
Laboratory results are as follows:
 The patient's creatinine was 1.4 mg/dL 3 months ago.  Which of the following is the most likely cause of the acute renal dysfunction in this patient?

Accepted Answer

11ec193a_9901_eb8c_853d_2fafa0e49537_MD0002_00 This patient has acute kidney injury and electrolyte abnormalities while on tacrolimus and fluconazole; this should raise suspicion for calcineurin inhibitor nephrotoxicity. Calcineurin inhibitors (eg, tacrolimus, cyclosporine) are common immunosuppressants used in organ transplantation; toxicity may be due to medication-induced vasoconstriction leading to renal ischemia. Patients can have declining glomerular filtration rates and a variety of metabolic abnormalities, including hyperkalemia, hyperuricemia, hypophosphatemia, hypomagnesemia, hypercalciuria, and possibly metabolic acidosis. Significant hypertension may also be present. Toxicity is dose-dependent. Calcineurin inhibitors are metabolized by cytochrome P450 3A4; levels are increased by other drugs that are metabolized by this enzyme (eg, azole antifungals, macrolides, non-dihydropyridine calcium channel blockers). Biopsy is often required to rule out acute rejection; histologic findings are nonspecific, but calcineurin inhibitor nephrotoxicity is suggested by the absence of signs of acute rejection (eg, interstitial inflammation, intimal arteritis, tubulitis). Acute calcineurin inhibitor toxicity is usually reversible with drug cessation, although some patients develop residual chronic renal dysfunction. (Choice A) Although this patient has diabetes and an elevated blood glucose possibly indicating suboptimal control, diabetic nephropathy is typically slowly progressive over a period of years (as opposed to the acute change in this patient) and is associated with proteinuria. (Choice B) Acute graft rejection most commonly occurs within the first 6 months post-transplant, unless the patient is noncompliant with immunosuppression. In addition, significant proteinuria (>1 g) is often present. (Choice C) Hypertensive nephrosclerosis usually presents with a long history of hypertension, slowly rising creatinine, and mild proteinuria. Although this patient has hypertension, the elevated blood pressure is more likely due to tacrolimus rather than primary hypertension, given the electrolyte abnormalities. (Choice E) Recurrence of membranoproliferative glomerulonephritis could cause progressive renal failure and hypertension, but urinalysis would likely show hematuria, red blood cell casts, and proteinuria. Educational objective: Calcineurin inhibitors (eg, cyclosporine, tacrolimus) can cause nephrotoxicity that presents with declining glomerular filtration rates and metabolic abnormalities. Toxicity is dose-dependent; drugs metabolized by cytochrome P450 3A4 can increase toxicity. __________ References: Calcineurin inhibitor nephrotoxicity. (http://www.ncbi.nlm.nih.gov/pubmed/19218475)

Question 14

A 67-year-old man comes to the physician because of bloody urine.  This morning, he noticed gross hematuria with passage of a few small blood clots in his urine.  He also reports mild dysuria.  He has since continued to have grossly bloody urine with occasional small blood clots.  He denies fever, chills, back/flank pain, and bruising or bleeding at other sites.  He denies any history of urolithiasis or trauma.
His other medical problems include a history of granulomatosis with polyangiitis (Wegener's) diagnosed 3 years ago.  At that time, he was treated with 6 months of oral cyclophosphamide and tapering doses of prednisone.  He has subsequently been maintained on oral methotrexate.  He denies recent weight loss, arthralgias, or respiratory symptoms.
His blood pressure is 130/86 mm Hg, pulse is 84/min, and respirations are 16/min.  He is afebrile.  There are no bruises or petechiae.  He does not have any flank pain.  Cardiopulmonary examination is normal.
After sending a urine sample to the laboratory for culture, the following laboratory results are obtained:

Which of the following would have the highest diagnostic yield?

Accepted Answer

When hematuria is of renal glomerular or tubular/interstitial origin, a relatively small amount of blood is diluted by tubular fluid and urine. Also, tissue plasminogen and urokinase are present within the tubules and glomeruli. Consequently, glomerular and other intrarenal causes of hematuria are rarely, if ever, associated with the passage of clots into the urine. This patient has a history of cyclophosphamide exposure and presents with painless hematuria in the absence of urinary tract symptoms. Evaluation for bladder lesions via cystoscopy would have the highest diagnostic yield. Cyclophosphamide can induce a chemical cystitis and be associated with the development of bladder cancer. (Choice A) An abdominal CT to look for a renal tumor or stones is appropriate; however, given this patient's history, cystoscopy is of higher diagnostic yield. (Choice B and E) Measurement of ANCA, C-reactive protein, and ESR may help ascertain the activity of this patient's granulomatosis with polyangiitis. A renal biopsy can diagnose and classify kidney involvement in granulomatosis with polyangiitis. However, this patient has a non-glomerular source for his hematuria and cystoscopy is the diagnostic test of choice. (Choice D) The detection of dysmorphic red blood cells (cells with blebs or protrusions, so-called "Mickey-Mouse" head RBCs) in the urine is highly suggestive of a glomerular source of hematuria, as is the presence of RBC casts and > 500 mg/day of proteinuria. In this patient, the passage of urinary clots strongly suggests the presence of an extra-glomerular site of bleeding, and cystoscopy should be performed even if dysmorphic urinary RBCs are present. Educational objective: In patients with hematuria, the passage of blood clots in the urine indicates a non-glomerular source of urinary tract bleeding. Thus, evaluation should proceed accordingly. __________ References: Cyclophosphamide-induced bladder toxicity in Wegener's granulomatosis. (http://www.ncbi.nlm.nih.gov/pubmed/3358809) The significance of adult hematuria: 1,000 hematuria evaluations including risk-benefit and cost-effectiveness analysis. (http://www.ncbi.nlm.nih.gov/pubmed/2492350)

Question 15

A 36-year-old woman comes to the office due to recurrent dysuria.  She also has had dull pain in her right flank and cloudy urine that contains blood.  The patient has a history of recurrent urinary tract infections since becoming sexually active in high school.  Over the last year, she has had 3 infections accompanied by fever.  Her last urine culture grew Klebsiella pneumoniae.  The patient is in a monogamous relationship.  For contraception, she uses a diaphragm or her partner uses a condom, both with spermicidal coatings.
Temperature is 38.1 C (100.6 F), blood pressure is 114/70 mm Hg, and pulse is 95/min.  The abdomen is soft and nontender.  Mild right costovertebral angle tenderness is present on percussion.
Laboratory results are as follows:
 Which of the following would most likely treat the underlying cause of this patient's recurrent condition?

Accepted Answer

This patient's presentation-with hematuria, right flank pain, dysuria, a history of recurrent urinary tract infections (UTIs), and laboratory tests indicating very alkaline urine (pH >8) and a decreased glomerular filtration rate-is strongly suggestive of struvite stones. Struvite stones are caused by urease-producing bacteria (eg, Proteus, Klebsiella). These bacteria convert urea to ammonia, which raises the urine pH and crystallizes with magnesium and trivalent phosphate to form struvite crystals. Once present, struvite stones may rapidly expand over weeks to months and develop into a staghorn calculus, filling the entire renal collecting system. If left untreated, the stones will continue to seed infections, and urinary tract obstruction can lead to loss of kidney function. Eradication of staghorn calculi is difficult. Antibiotics alone do not eliminate the source of the infection, because the bacteria grow within the stone matrix and are not eradicated until the entire stone and its fragments are removed. In addition to antibiotics for the UTI, percutaneous nephrolithotomy, often with lithotripsy, is the preferred first-line therapy. Open surgical stone removal is indicated for morbidly obese individuals (in whom fluoroscopy is difficult) and for patients with a large stone burden and a distorted collecting system anatomy. Nephrectomy is reserved for patients with a staghorn stone in a chronically infected kidney that is nonfunctioning or poorly functioning. (Choice A) Spermicides have been linked to an increased frequency of UTIs in women. However, stopping the use of spermicides alone will not eliminate this patient's UTI or treat her struvite stone. (Choice B) High-volume fluid intake and allopurinol are effective for treating and preventing uric acid, but not struvite, stones. (Choice C) Postcoital antibiotics can help patients whose UTIs are linked to sexual intercourse. However, they would not eliminate this patient's source of infection (bacteria growing within the stone matrix) unless the entire stone and its fragments were removed. (Choice E) Urinary alkalization can be useful in patients with recurrent uric acid stones or calcium oxalate stones associated with low urine citrate excretion, but it is not useful in the prevention of struvite stones. Urinary acidification is occasionally used for treatment and prevention of recurrent struvite stones, but medical therapy alone is rarely successful and not considered first-line therapy. Educational objective: Recurrent urinary tract infections in patients with alkaline urine should raise the possibility of a struvite stone. Antibiotics alone do not remove the source of the infection; elimination of the stone is required. __________ References: Reduced glomerular filtration rate and hypercalciuria in primary struvite nephrolithiasis. (http://www.ncbi.nlm.nih.gov/pubmed/3430961) Long-term results of percutaneous nephrolithotomy for treatment of staghorn stones. (http://www.ncbi.nlm.nih.gov/pubmed/21166763)

Question 16

A 40-year-old man comes to the emergency department due to acute flank pain and dysuria. He has no associated fever, joint pain, or suprapubic pain. The patient was discharged 5 days ago following hospitalization for central nervous system toxoplasmosis. He has long-standing AIDS (most recent CD4 count: 150/mm³) and had not been compliant with either antiretroviral treatment or trimethoprim-sulfamethoxazole prophylaxis therapy for several months prior to admission. While in the hospital, the patient was started on sulfadiazine and pyrimethamine, and antiretroviral treatment was reinstituted. Temperature is 37 C (98.6 F), blood pressure is 122/78 mm Hg, and pulse is 98/min. Mucous membranes are dry. The abdomen is soft, and bilateral costovertebral angle tenderness is present. No rash is present. Laboratory studies are as follows: A urinary catheter is placed and produces 10 mL of urine during 6 hours of observation in the emergency department. Which of the following is most likely to confirm the diagnosis in this patient?

Accepted Answer

11ec193a_98fb_0dac_853d_8d0f0848fb9d_MD0002_00 This patient has acute kidney injury (AKI) with hematuria, pyuria, and bilateral costovertebral angle tenderness. The recent initiation of sulfadiazine should raise suspicion for crystal-induced AKI, which occurs when poorly soluble drugs precipitate within the renal tubules. Factors favoring crystal formation include exposure to high doses of the drug, dehydration (increases intratubular concentration), and acidic urinary pH (occurs with uric acid, sulfonamides, and methotrexate). Patients are often asymptomatic, but can have flank pain; symptoms typically occur within a week of drug initiation. Diagnosis is confirmed by observation of characteristic crystals on urinalysis when the patient is taking a known inciting drug. Hematuria and pyuria are also commonly noted. Nearly 30% of patients on sulfadiazine develop AKI, primarily due to the drug's insolubility at a urinary pH of ≤5.5. Sulfonamides can form needle-shaped, rosette, or clumped ("stacks of wheat") crystals that can be identified on urinalysis. Prevention and treatment of sulfadiazine-induced AKI include adequate hydration (3 L/day) and alkalinization of the urine to a pH of >7.15 to increase solubility. In patients with suspected sulfadiazine-induced AKI, renal ultrasound can be obtained to complete the evaluation but is unlikely to confirm the diagnosis. Ultrasonography can be normal, show sludge or small calyceal stones (due to sulfonamide precipitation), or reveal hydronephrosis (in rare cases where urolithiasis develops and causes obstructive uropathy). However, these findings are nonspecific and are unlikely to change initial management with fluids and urine alkalinization to solubilize the crystals. If urolithiasis is suspected in a nonpregnant patient, noncontrast CT scan is preferred to ultrasound as it is more sensitive and accurate (Choice B). (Choice A) Cystoscopy can detect bladder cancer or stones, which usually present with painless hematuria or irritative voiding symptoms. This patient's flank pain and costovertebral tenderness are more consistent with an upper urinary tract etiology. (Choice C) Pyelonephritis causes flank pain and costovertebral angle tenderness, although it is typically unilateral. However, patients who develop AKI from pyelonephritis are typically quite ill; fever, chills, and hypotension would be expected. (Choice E) Acute interstitial nephritis commonly presents with fever, rash, and eosinophilia. Urinalysis classically shows urine eosinophils and white blood cell casts (not seen in this patient). In addition, pain is uncommon. Educational objective: Crystal-induced acute kidney injury occurs when poorly soluble drugs precipitate in the renal tubules. Sulfadiazine is insoluble at a pH of ≤5.5; prevention and treatment include hydration and alkalinization of the urine to a pH of >7.15 to increase solubility. __________

Question 17

A 28-year-old woman comes to the office because of frequent urination. She urinates approximately every 30 to 60 minutes during the day, which makes it difficult to concentrate at work and attend meetings. She also gets up 1 to 2 times per night to urinate. The patient drinks "a lot of fluid to stay caught up." She says that her 'migraines' have worsened recently and she occasionally feels nauseated. She got a new pair of glasses due to worsening of her vision, which she attributes to spending a lot of time at work. She has had no lower abdominal pain or dysuria. Her other medical problems include anxiety disorder and knee trauma that she sustained three months ago while jogging. She required arthroscopic surgery and took opioid medications for pain control for two weeks. She has not experienced any knee pain since. Her BMI is 18 kg/m². Physical examination shows no abnormalities. Laboratory results are as follows: Urine pregnancy test is negative. Eight hours following a water deprivation, her weight remains unchanged and her plasma and urine osmolalties are 284 and 650 mOsm/kg H₂O respectively. Which of the following is the most likely diagnosis?

Accepted Answer

11ec193a_98fe_1af5_853d_a5e4aaf0d902_MD0002_00 This patient presents with polyuria with dilute urine and increased water intake, which is usually due to diabetes insipidus (DI) or primary polydipsia (summarized in the above table). However, the polyuria with water loss is appropriate in polydipsia but inappropriate in DI. Serum Na > 145 mEq/L with a urine osmolality < serum osmolality excludes primary polydipsia and suggests DI. However, patients with an intact thirst mechanism will have adequate water intake to compensate for the water loss and may have a normal sodium level (as in this patient). In cases where a clinical diagnosis is difficult, a water deprivation test should be done to confirm the diagnosis. However, patients suspected of having nephrogenic DI should receive desmopressin without water deprivation and be monitored for a lack of response. water deprivation test This patient is able to concentrate her urine and preserve her plasma osmolality at a normal level in response to observed water deprivation. This suggests that antidiuretic hormone (ADH) release and action are both intact and that the cause of her polyuria is excess fluid intake (primary polydipsia). Her urinary concentration may be subnormal due to chronic water diuresis. (Choice A) Amphetamine abuse can lead to hyponatremia due to increased fluid intake (from hyperthermia) and persistent secretion of ADH that decreases water excretion. This patient's water deprivation test is more consistent with primary polydipsia. (Choice B) Central diabetes insipidus would be associated with weight loss, increasing plasma osmolality (due to renal water loss), and urine osmolality < 300 mOsm/kg in response to water deprivation. (Choice C) Nephrogenic diabetes insipidus would not be associated with an increase in urine osmolality to this level with water deprivation. (Choice E) Chronic diuretic use/abuse is usually associated with hypokalemic alkalosis, which is not present in this patient. Educational objective: Polyuria and polydipsia can be due either to a solute diuresis (usually uncontrolled diabetes mellitus with glycosuria) or a water diuresis. Water diuresis can be due to impaired ADH secretion (central DI), impaired action of ADH on the kidney (nephrogenic DI), or excess fluid intake. The response to controlled/observed water deprivation differentiates among these possibilities. __________ References: Disorders of antidiuretic hormone. (http://www.ncbi.nlm.nih.gov/pubmed/3042388)

Question 18

A 54-year-old woman with end-stage renal disease secondary to diabetic nephropathy and hypertension comes to the office due to easy fatigability and tiredness.  The patient experienced similar symptoms 6 months ago, but they improved after starting erythropoietin therapy for anemia.  Over the past several weeks, the symptoms have recurred but she has had no chest pain, dyspnea, palpitations, syncope, melena, or hematochezia.  The patient receives 3-4 hours of maintenance hemodialysis 3 times a week.  She has no drug allergies.
Blood pressure is 130/78 mm Hg and pulse is 70/min with no orthostatic changes.  She weighs 68 kg (150 lbs), which is her 'dry weight'.  There are no heart murmurs.  Abdominal examination shows no organomegaly and stool occult blood testing is negative.
Laboratory studies are as follows:

Hemoglobin was 8.2 g/dL and 10.1 g/dL 6 months and 4 months ago, respectively.
Which of the following is the most appropriate next step in management of this patient's anemia?

Accepted Answer

11ec193a_98fb_d0fe_853d_c7c02967b195_MD0002_00 This patient initially had an appropriate response to erythropoietin-stimulating agent (ESA) therapy but now has worsening anemia. Iron deficiency is the most common cause of erythropoietin resistance. Patients with end-stage renal disease (ESRD) are at risk for iron deficiency due to: Absolute iron deficiency: Blood loss (eg, gastrointestinal, blood draws) or vigorous hematopoiesis during ESA therapyFunctional iron deficiency: Impaired mobilization of iron due to elevated hepcidin levels (ie, anemia of chronic disease) or because iron cannot be mobilized rapidly enough to keep up with hematopoiesis after ESA administration Absolute iron deficiency: Blood loss (eg, gastrointestinal, blood draws) or vigorous hematopoiesis during ESA therapy Absolute iron deficiency: Blood loss (eg, gastrointestinal, blood draws) or vigorous hematopoiesis during ESA therapy Functional iron deficiency: Impaired mobilization of iron due to elevated hepcidin levels (ie, anemia of chronic disease) or because iron cannot be mobilized rapidly enough to keep up with hematopoiesis after ESA administration Functional iron deficiency: Impaired mobilization of iron due to elevated hepcidin levels (ie, anemia of chronic disease) or because iron cannot be mobilized rapidly enough to keep up with hematopoiesis after ESA administration Normocytic anemia can be seen in the early stages of absolute iron deficiency (ie, before microcytosis develops) as well as in functional iron deficiency (ie, anemia of chronic disease), explaining this patient's normal mean corpuscular volume. The diagnosis of absolute iron deficiency in patients with chronic kidney disease (CKD) is complex and is commonly based on parameters such as low transferrin saturation (eg, ≤20%) and ferritin (eg, ≤200 ng/mL in hemodialysis patients) levels. All patients with ESRD on ESA therapy should be treated with iron, regardless of the results of iron studies, unless ferritin is >500 ng/mL. It is likely that this patient had limited iron stores that were rapidly depleted following initiation of ESA therapy. For completion, she should also be evaluated for gastrointestinal blood loss. (Choices B and D) Pure red blood cell aplasia is a hypoproliferative disorder that can be caused by anti-erythropoietin antibodies. Other hypoproliferative disorders (eg, myelodysplastic syndrome) can be diagnosed with bone marrow biopsy. However, hypoproliferative disorders are associated with increased serum iron levels due to reduced iron utilization. In addition, the brand of epoetin alfa most commonly associated with anti-erythropoietin antibodies has been removed from the market. Although bone marrow biopsy is the gold standard for diagnosis of absolute iron deficiency, parameters such as transferrin saturation and ferritin are commonly used to identify it in patients with CKD. (Choice C) Inadequate hemodialysis can cause ESA hyporesponsiveness, but this patient has maintained her dry weight and does not have symptoms of volume overload. (Choice E) Red blood cell transfusions come with significant risks (eg, volume overload, transfusion reaction) and are reserved for severe anemia (hemoglobin <7 g/dL) in patients unresponsive to ESAs after iron supplementation. Educational objective: Iron deficiency is the most common cause of erythropoietin resistance in patients with end-stage renal disease (ESRD). All patients with ESRD receiving erythropoietin-stimulating agents should be treated with iron, regardless of results of iron studies unless ferritin >500 ng/mL. __________ References: Pattern of resistance to erythropoietin-stimulating agents in chronic kidney disease. (http://www.ncbi.nlm.nih.gov/pubmed/21697809)

Question 19

A 40-year-old woman is referred for evaluation of chronic kidney disease (CKD).  She has a two-year history of intermittent back, bilateral flank, and central abdominal pain.  She has lost approximately 15 lbs (6.8 kg) and is easily fatigued.  She had an episode of deep venous thrombosis one year ago that has not recurred.  She has noticed mild bilateral pedal edema.  She works in an office and denies using tobacco or illicit drugs.  Up until two years ago, she felt well and is unaware of any chronic medical problems.  Her current medications include over-the-counter acetaminophen and ibuprofen for pain control.
Her examination is unremarkable except for diffuse mild abdominal tenderness and bilateral, 2+, brawny lower extremity edema.
Laboratory results are as follows:

On renal ultrasound, both kidneys measure 12.5 cm (normal 9-12 cm).  There is bilateral clubbing and mild-to-moderate dilation of the calices without dilation of the mid or distal ureters.
Which of the following is the most likely diagnosis?

Accepted Answer

11ec193a_9902_87ce_853d_49b7c704465f_MD0002_00 This patient's presentation is most consistent with retroperitoneal fibrosis, a rare disorder causing mid and distal ureteral obstruction without the usual ureteric dilation seen in obstructive uropathy. Retroperitoneal fibrosis is usually idiopathic, but it has been associated with drugs (e.g., beta blockers, bromocriptine, ergots), malignancy (e.g., lymphoma), infections (e.g., TB), and radiation therapy. Retroperitoneal fibrosis is the result of chronic inflammation with fibroblast proliferation, leading to chronic periaortitis and involvement of surrounding structures. Patients typically present with pain that is dull, noncolicky, and occurring in a girdle distribution. Abdominal CT is preferred along with biopsy when clinically indicated. Treatment involves steroids, relieving ureteral obstruction (e.g., percutaneous nephrostomy tube or surgery), and treating the underlying disorder. This patient has many findings of retroperitoneal fibrosis, including history of long-standing abdominal pain, weight loss, previous DVT (likely due to venous obstruction), lymphedema, typical ultrasound findings, renal failure with bland urinary sediment, and elevated ESR and CRP. (Choice A) Advanced cervical cancer usually spreads into the broad ligament and causes obstruction of one or both ureters with significant ureteric dilation, which is not consistent with this patient's findings. (Choice B) Chronic glomerulonephritis usually presents with proteinuria, which is not present in this patient. (Choice C) Chronic interstitial nephritis usually presents with casts and more active urinary sediment (e.g., WBCs, RBCs), but it does not cause caliceal clubbing. (Choice D) Renal tuberculosis typically presents as a combination of upper and lower genitourinary tract disease with hematuria, sterile pyuria, ureteric strictures, contracted bladder; and calcification of the vas deferens, seminal vesicles, or prostate. Educational objective: Retroperitoneal fibrosis typically presents with nonspecific pain in the low back, flank, or abdomen. Patients usually have progressively worsening periaortic fibrosis that leads to kidney injury, ureteral obstruction without ureteral dilation, and possible IVC obstruction with edema and DVT. Treatment involves steroids, relieving the obstruction, and treating the underlying cause. __________ References: Idiopathic retroperitoneal fibrosis: prospective evaluation of incidence and clinic-radiologic presentation. (http://www.ncbi.nlm.nih.gov/pubmed/19593223) Obstructive nephropathy as a result or retroperitoneal fibrosis: a review of its pathogenesis and associations. (http://www.ncbi.nlm.nih.gov/pubmed/10495799)

Question 20

A 43-year-old man comes to the physician because of weakness and arthralgias for the last four months.  He also has a pruritic rash on his legs that appeared two months ago.  He denies fever or chills and his weight has been stable.
His blood pressure is 140/90 mm Hg and pulse is 84/min.  A rash is present on both lower extremities below the knees that consist of many erythematous macules.
Laboratory results are as follows:

Which of the following would be most helpful in establishing the diagnosis in this patient?

Accepted Answer

11ec193a_98fc_bb60_853d_5923234ddd45_MD0002_00 This patient's presentation is consistent with mixed cryoglobulinemia causing glomerulonephritis. Cryoglobulinemia is classified as either type I or mixed (types II and III). Diagnosis is suggested by elevated cryoglobulins (cryocrit), ESR, CRP, autoantibodies (e.g., RF, ANA), and clinical symptoms (summarized in the above table). Mixed cryoglobulinemia is commonly associated with hepatitis C and elevated liver function tests, and more than 60% of patients with hepatitis C have cryoglobulins. Approximately 20% of patients with cryoglobulinemia develop renal disease, which is usually glomerulonephritis from hepatitis C-containing immune complexes. Patients with hepatitis C-associated cryoglobulinemia have a higher risk of developing lymphoma up to 5-10 years later. Treatment involves eradicating HCV, immunosuppression (eg, prednisone, cyclophosphamide), and/or plasmapheresis for moderate-severe cryoglobulinemia. (Choice A) Anti-phospholipid antibody syndrome (APS) can also cause anemia, thrombocytopenia, livedo reticularis, and glomerulonephritis. However, this patient has increased AST and ALT and low albumin, suggesting chronic liver disease. Also, most patients with APS have thrombotic episodes (eg, DVT, strokes). (Choice B) Bone marrow biopsy is more useful in type I cryoglobulinemia to diagnose an underlying hematological condition with bone marrow involvement. However, this patient likely has mixed cryoglobulinemia and would not need a bone marrow biopsy. (Choice C) Serum protein electrophoresis can help diagnose underlying plasma cell disorders (eg, multiple myeloma or Waldenström's macroglobulinemia), but they are associated more with type I than mixed cryoglobulinemia. (Choice D) Heroin users can develop membranous nephropathy (due to hepatitis B), membranoproliferative glomerulonephritis (due to hepatitis C), or focal segmental glomerulosclerosis. However, this patient's presentation is consistent with vasculitis. Viral serologies are more likely to give a correct diagnosis in this patient given the low white cell count, thrombocytopenia, and increased AST/ALT. Educational objective: Mixed cryoglobulinemia is commonly associated with hepatitis C and can cause glomerulonephritis. Treatment includes eradicating hepatitis C and immunosuppression and/or plasmapheresis for cryoglobulinemia. __________ References: Mixed cryoglobulinemia. (http://www.ncbi.nlm.nih.gov/pubmed/18796155) Hepatitis C virus infection in patients with essential mixed cryoglobulinemia. (http://www.ncbi.nlm.nih.gov/pubmed/1326246)

Exam 3: Office/Health Center