Question 1

A 10-month-old boy is brought to clinic for evaluation of decreased activity.  The patient has been progressively tired over the past few weeks.  He normally is able to crawl and pull up to a stand, but lately he is so tired that he prefers to sit still.  The boy is primarily breastfed and eats some pureed fruits.  He has 6 or 7 wet diapers and 3 soft stools per day.  He has no known medical conditions or prior hospitalizations.  The patient lives with his parents and 3-year-old sister, none of whom have chronic medical conditions.  His parents are originally from Ghana and moved to the United States 4 years ago.  Temperature is 36.7 C (98 F) and pulse is 100/min.  Examination shows mild conjunctival pallor.  The lungs are clear to auscultation.  A 2/6 systolic murmur is auscultated over the precordium.  The abdomen is soft and nontender, and bowel sounds are present.  Laboratory results are as follows:  Which of the following is the most likely cause of this child's anemia?

Accepted Answer

Explanation: 11ec2b69_c166_73f9_8f63_130e4de7bc87_MD0005_00 Iron deficiency is the most common cause of anemia in infants in the United States. It is typically due to inadequate dietary iron, as in breastfed infants age >6 months who do not eat enough iron-rich foods or any infant who drinks cow's milk before age 1 year. Premature infants are also at increased risk due to inadequate iron stores. Most children with iron deficiency are asymptomatic; however, if symptomatic, the most common findings are lethargy, irritability, pallor, and a systolic flow murmur, as seen in this patient. Severe anemia can cause cardiomegaly and tachypnea. Classic laboratory findings include hemoglobin <11 g/dL, often accompanied by low mean corpuscular volume (MCV), elevated red blood cell (RBC) distribution width, and a low RBC count. A Mentzer index (MCV/RBC) >13 is also suggestive of iron deficiency and can help differentiate it from thalassemia; in this patient, the Mentzer index is 65/3.5 = 18.6. Alpha and beta thalassemias are also microcytic but characterized by a Mentzer index <13 (Choices C and D). Although breastfeeding is recommended for at least the first year of life, iron-fortified cereals, pureed meats, and foods rich in vitamin C (to enhance iron absorption) should be introduced around age 6 months. In addition to iron-rich foods, this patient will also require oral iron therapy to replenish iron stores. (Choice B) Chronic lead ingestion causes normocytic, hemolytic anemia. This patient with a low MCV and poor dietary iron intake is more likely to have iron deficiency anemia. (Choice E) Glucose-6-phosphate dehydrogenase deficiency is an X-linked disorder that may be asymptomatic until exposure to oxidant medications or substances causes acute hemolytic anemia. Acute hemolytic anemia is typically characterized by a normal MCV. In addition, this patient's history is suggestive of a chronic, gradual process rather than an acute event. Educational objective: Iron deficiency anemia is common in infancy and is characterized by hemoglobin <11 g/dL, low mean corpuscular volume, and Mentzer index >13. Although breast milk provides sufficient iron for the first few months of life, introducing iron-rich foods (eg, pureed meats) around age 6 months is necessary to prevent iron deficiency. References: Iron deficiency anemia in predominantly breastfed young children. (http://www.ncbi.nlm.nih.gov/pubmed/24953965) Diagnosis and prevention of iron deficiency and iron-deficiency anemia in infants and young children (0-3 years of age). (http://www.ncbi.nlm.nih.gov/pubmed/20923825) Timing of the introduction of complementary foods in infancy: a randomized controlled trial. (http://www.ncbi.nlm.nih.gov/pubmed/23147979)

Question 2

A 65-year-old Caucasian female presents to the emergency department with progressive shortness of breath on minimal exertion and fatigue.  She was diagnosed with myelodysplasia two years ago, and has been receiving supportive therapy with frequent RBC transfusions.  Her last transfusion was 3 months ago.  She experienced an episode of severe pneumonia one year ago that required hospitalization and IV antibiotic therapy.  She is taking no medications currently and has no known allergies.  Her blood pressure is 120/70 mmHg and heart rate is 95/min.  Physical examination reveals pallor.  Systolic murmur with intensity of II/VI is heard over the cardiac apex.  Laboratory findings are significant for hematocrit of 24% and hemoglobin level of 5.7 mg/dL.  You consider RBC transfusion in this patient.  Blood grouping and cross-matching are done, but the blood bank is unable to find suitable blood.  This is the first time such an incompatibility has occurred.  What is the most likely reason for this incompatibility?

Accepted Answer

Explanation: After blood is ordered for transfusion, the following compatibility testing is usually performed. First, the patient's ABO and Rh types are determined. After this, the patient's serum is screened for unexpected antibodies, a procedure called pretransfusion antibody screening. Pretransfusion antibody screening is intended to detect any of all clinically significant RBC antibodies. If negative, the patient can be safely transfused. If positive, further investigation is usually warranted to evaluate the identity of the antibody. The major problem that leads to difficulties finding cross-matched blood in patients with a history of multiple transfusions is alloantibodies (e.g., in patients with sickle cell anemia or myelodysplasia). The most commonly implicated RBC antigens in that case are E, L and K. Moreover, these patients tend to develop multiple alloantibodies that make finding compatible blood even more difficult. (Choices C and E)Finding ABO and Rh-compatible blood is usually not a big challenge. (Choice A)Autoantibodies are less likely to cause difficulties in cross-matching in this patient; they are commonly implicated as a cause of the incompatible cross-match in patients with autoimmune anemia and taking certain drugs (e.g., methyldopa and procainamide). (Choice D)HLA allosensitization increases risk of graft rejection in patients awaiting organ or bone marrow transplantation and platelet refractoriness in those requiring subsequent platelet transfusion support. Remember that RBCs do not express HLA antigens. Educational Objective: The major problem that leads to difficulties finding cross-matched blood in patients with a history of multiple transfusions is alloantibodies.

Question 3

A 55-year-old man with a history of chronic low back pain comes to the physician with a 3-week history of progressive right shoulder pain and a 1-week history of worsening lower back pain.  He has tried several over-the-counter medications without significant relief.  He smokes 2 packs daily and consumes alcohol occasionally.  A chest x-ray reveals a right superior lobe mass.  Which of the following additional findings, if present, would indicate a worse prognosis requiring urgent intervention?

Accepted Answer

Explanation: 11ec2b69_c169_f66e_8f63_cf2caa4e510f_MD0005_00 The description in the vignette is consistent with superior pulmonary sulcus (Pancoast) tumor, generally a subset of non-small cell lung cancer. Shoulder pain is the most common initial presentation. The history and physical examination may assist in assessing the extent of neoplastic spread and determining prognosis. Pancoast syndrome consists of shoulder pain (50%-90%), Horner's syndrome (15%-50%), and hand muscle atrophy and weakness (10%-20%). However, asymmetric lower-extremity deep-tendon reflexes, particularly in the setting of back pain, suggest that the tumor has spread to the spinal cord. Spinal cord compression develops in up to 25% of patients with Pancoast tumor during the course of the disease and may result in paraplegia. Early recognition and appropriate therapy (which may include corticosteroid therapy, surgery, and radiation) is imperative to preserve neurologic function and patient autonomy. 11ec2b69_c169_f66f_8f63_f5cbf37a4d07_MD0005_00 (Choices A and B) Brachial plexopathy is a typical complication of superior sulcus tumor that may lead to atrophy of the internal muscles of the hand and asymmetric upper-extremity deep-tendon reflexes. (Choice D) Pupil size asymmetry and asymmetric palpebral fissures result from invasion of the paravertebral sympathetic chain (Horner's syndrome). Horner's syndrome is considered to be a poor prognostic sign, but it is not immediately dangerous. (Choice E) Streaky hemoptysis and weight loss are typical symptoms of lung cancer that are not dangerous per se. Given the peripheral location of Pancoast tumors, pulmonary symptoms tend to occur at a more advanced stage. Educational objective: Spinal cord compression develops in up to 25% of patients with Pancoast tumor during the course of the disease. Early recognition and appropriate therapy are imperative to preserve neurologic function and patient autonomy. References: Superior pulmonary sulcus tumors and Pancoast's syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/9358132)

Question 4

A 43-year-old male presents to your office with several months history of progressive fatigue and occasional palpitations.  He had three episodes of acute respiratory infections over the last year; otherwise, his past medical history is insignificant.  He smokes two packs of cigarettes daily and consumes alcohol occasionally.  He is not taking any medications and denies drug abuse.  He has been sexually active with several partners recently.  The physical examination is insignificant.  His laboratory values are:  His HIV test results are negative.  Which of the following is the best next step in the management of this patient?

Accepted Answer

Explanation: Normocytic/normochromic anemia is a very broad category. It may be caused by two large groups of disorders: 1) diseases with decreased red blood cell production, and 2) hemolytic disorders. To determine the predominant pathophysiologic mechanism of anemia in this patient, a reticulocyte count must be obtained. An elevated reticulocyte count indicates hemolysis as the cause of anemia; other findings associated with increased RBC destruction should be sought (e.g. elevated indirect bilirubin level, decreased haptoglobin, increased LDH, splenomegaly). A low reticulocyte count indicates a hypoproliferative state; renal disease, hypothyroidism and aplastic anemias may be present. (Choice D) Further evaluation of hemolytic anemias may include hemoglobin electrophoresis and Coombs' test. (Choice A)Anemia of chronic disease may present as normocytic/normochromic anemia; ESR and serum C-reactive protein measurements may help in the diagnosis. (Choice B)Iron deficiency anemia is microcytic/hypochromic. (Choice E)Bone marrow biopsy is not indicated at this stage. Educational Objective: Obtaining a reticulocyte count helps in determining the predominant pathophysiologic mechanism of normocytic/normochromic anemia.

Question 5

An 8-month-old boy with sickle cell disease is brought to an urgent care center by his parents following several hours of intermittent crying.  Yesterday afternoon, the patient had been active and crawling around, but he seemed irritable in the evening and was awake most of the night.  Today, his parents noticed swelling of his hands and feet, which appear painful to the touch.  The pain seems to be only minimally relieved with over-the-counter acetaminophen and ibuprofen.  The boy has been breastfeeding less than usual due to fussiness but has been voiding appropriately.  The patient has never been hospitalized.  He takes oral penicillin prophylaxis and a vitamin D supplement.  Immunizations, including an annual influenza vaccination, are up to date.  Temperature is 36.7 C (98 F), blood pressure is 90/60 mm Hg, pulse is 158/min, and respirations are 32/min.  Pulse oximetry is 98% on room air.  Physical examination shows a fussy infant who can be consoled for short periods of time but appears restless and grimaces occasionally during the examination.  There is symmetric swelling of the hands and feet.  There are no rashes or skin abrasions.  Lungs are clear to auscultation, and there are no retractions or use of accessory muscles.  The abdomen is soft, nontender, and nondistended; the spleen is not palpable.  The remainder of the examination is normal.  The last dose of ibuprofen was given 1 hour ago.  Which of the following is the most appropriate next step in management of this patient?

Accepted Answer

Explanation: 11ec2b69_c169_5a2d_8f63_97cf6764aade_MD0005_00 This patient with symmetric swelling and pain of the hands and feet in the setting of known sickle cell disease (SCD) has dactylitis (hand-foot syndrome). Dactylitis, resulting from vaso-occlusion of the blood vessels supplying the metacarpals and metatarsals, may be the earliest manifestation of SCD in young children (ages 6 months to 4 years). Similar to other vaso-occlusive episodes, triggers include stress, illness, temperature changes, and dehydration. Low-grade fever may also be present in addition to pain. Initial radiographs reveal only soft-tissue swelling; recurrent episodes can lead to a mottled appearance of the bones. Although most children with SCD are diagnosed by hemoglobin electrophoresis on newborn screening, the presence of dactylitis in a previously healthy child should prompt evaluation for SCD. Treatment of dactylitis involves pain control, hydration, and application of heat. Oral nonsteroidal anti-inflammatory drugs (NSAIDs) and oral opioids are typically initiated for mild to moderate pain. Because this patient still appears uncomfortable after treatment with NSAIDs, a short-acting oral opioid (eg, oxycodone) should be given. If the pain fails to improve, intravenous opioids are indicated. (Choice A) Cold compresses are not recommended as they can trigger local intravascular sickling and worsen vaso-occlusive pain episodes. In contrast, heat packs help by promoting vasodilation. (Choices B and E) Oral codeine and tramadol are contraindicated in children age <12 because ultra-rapid metabolism of codeine and tramadol causes an unpredictably high concentration of the active drug in the body, which can result in respiratory depression and death. (Choice C) Hydroxyurea reduces the frequency of vaso-occlusive episodes in patients with SCD but may take several months to take effect. It is not used in the treatment of an acute vaso-occlusive episode. Educational objective: Dactylitis presents in young children with sickle cell disease as symmetric swelling and pain of the hands and feet. Treatment includes pain control (eg, nonsteroidal anti-inflammatory drugs, oral opioids), hydration, and application of heat. References: Sickle cell disease. (http://www.ncbi.nlm.nih.gov/pubmed/20301551) Current management of sickle cell anemia. (http://www.ncbi.nlm.nih.gov/pubmed/23709685)

Question 6

A 48-year-old woman complains of persistent fatigue and daytime sleepiness.  Her other medical problems include hypertension and rheumatoid arthritis.  Her medications include naproxen, enalapril, and a multivitamin supplement with iron.  She has no known drug allergies.  Vital signs are within normal limits.  Examination shows conjunctival pallor and bilateral hand joint deformities with tenderness to palpation at metacarpophalangeal joints.  Stool testing for occult blood is negative. Laboratory results are as follows:
 Which of the following would be the most appropriate next step in managing this patient's anemia?

Accepted Answer

Explanation: 11ec2b69_c163_1891_8f63_3944eea29597_MD0005_00 Anemia of chronic disease (ACD, anemia of chronic inflammation) is a common complication of rheumatoid arthritis and other inflammatory diseases. The precise etiology is not fully understood but is generally thought to be due to suppression of hematopoiesis by inflammatory cytokines. Hematologic studies typically show a low serum iron, elevated ferritin levels, and normal transferrin saturation (approximately 25% of ACD patients may have low transferrin saturation). Mean corpuscular volume is usually low-normal to mildly decreased. ACD is usually a relatively mild anemia, but approximately 20% of patients may have hemoglobin <8 g/dL. In these more severe cases, clinicians should rule out additional concurrent causes of anemia such as iron deficiency, myelodysplasia, and thalassemia. The foundation of treatment for ACD is addressing the underlying inflammatory disorder. In rheumatoid arthritis, anti-TNF-α antibody (eg, infliximab) infusions have been shown to lessen the severity of anemia. If patients have low or inappropriately normal erythropoietin levels, they may respond to injections of erythropoietin or darbepoetin. Patients with appropriately elevated erythropoietin levels (especially >500 mU/mL) do not respond. Those who have severe, symptomatic anemia who do not improve with initial measures may need periodic red cell transfusions. (Choice A) Folinic acid (leucovorin) is a folic acid derivative. It can be given orally or parenterally to counteract the effects of antifolate drugs such as methotrexate used in autoimmune disorders and cancer. Folinic acid would not be helpful in this patient, who is not on methotrexate. (Choice C) Iron supplementation may be useful in patients with rheumatoid arthritis and ACD who have co-existing iron-deficiency anemia, which can result from gastrointestinal bleeding secondary to drug therapy or decreased absorption of dietary iron. If oral supplementation is not adequately absorbed, as may occur in patients with rheumatoid arthritis, parenteral iron may be needed. However, supplemental iron would not be helpful in patients such as this who have adequate iron stores. (Choice D) Plasmapheresis is used to reduce levels of circulating autoantibodies in conditions such as Guillain-Barré syndrome, myasthenia gravis, and thrombotic thrombocytopenic purpura. It has been used historically for rheumatoid arthritis but is no longer recommended and is not a standard treatment for anemia of chronic disease. (Choice E) Splenectomy can be considered in patients with hypersplenism and hemolytic anemia (eg, autoimmune hemolytic anemia, hereditary spherocytosis). ACD, however, is not due to hypersplenism or hemolysis, and splenectomy would not be helpful. Educational objective: Anemia of chronic disease (anemia of chronic inflammation) is a common complication of inflammatory conditions such as rheumatoid arthritis. Management generally involves treating the underlying condition and ruling out concurrent causes of anemia. Anti-TNF-α agents improve anemia of chronic disease in patients with rheumatoid arthritis. References: Anaemia in inflammatory rheumatic diseases. (http://www.ncbi.nlm.nih.gov/pubmed/23147894)

Question 7

A 13-month-old boy is brought to the clinic for a well-child visit.  His father says that the child has not been eating as much solid food since he started walking.  The parents think that he is "too busy exploring to eat" and have been supplementing his diet with whole milk in a cup that he carries with him.  The patient's daily diet consists of 900 mL (30 oz) of whole cow's milk, rice, and occasional fruits and vegetables.  He eats and drinks without gagging or choking; he can hold a spoon and feed himself finger foods.  The child was born at term.  Weight, height, and head circumference are at the 10th percentile for age.  Examination shows a pale child who is playing in the examination room.  The anterior fontanelle is open.  Cardiac examination reveals a normal rhythm with no murmurs.  The abdomen is soft, nontender, and without hepatomegaly.  The skin has normal turgor and capillary refill is <2 seconds.  Complete blood count shows a hemoglobin of 9.2 g/dL.  The most likely diagnosis is discussed with the parents.  Without treatment, this patient is at risk for which of the following long-term complications?

Accepted Answer

Explanation: 11ec2b69_c167_856b_8f63_bd76dbcf3bc4_MD0005_00 This child with excessive cow's milk intake (>20 oz/day), a diet lacking in iron-rich foods, pallor, and anemia likely has iron deficiency anemia (IDA). Because IDA is the most common nutritional deficiency in children, universal screening for IDA is recommended around age 1. A presumptive diagnosis is made in infants and children with a hemoglobin <11 g/L. Further testing (eg, peripheral smear, red blood cell indices, electrophoresis) is not necessary unless the patient has a history of chronic disease or a family history of anemia or hemoglobinopathy. Microcytic, hypochromic red blood cells (see black arrows) are seen on peripheral smear. hypochromic red blood cells Initial treatment is with oral ferrous sulfate. Iron is essential for neuronal myelination, migration, and differentiation; chronic deficiency can lead to psychomotor delay and neurocognitive impairment. With iron supplementation, gross motor skills usually improve; however, the remaining cognitive effects may be irreversible. (Choice A) An aplastic crisis may occur in a patient with parvovirus B19 infection and an underlying hemolytic anemia (eg, spherocytosis, sickle cell disease). This patient is asymptomatic and has no medical problems, making iron deficiency the most likely cause of anemia. (Choice B) Ataxia can result from deficiency in vitamin B₁₂, which is found in dairy and animal products (eg, meat, fish, eggs). Vitamin B₁₂ deficiency would be unlikely in an otherwise healthy child with adequate milk intake. ₁₂ ₁₂ (Choice C) Avascular osteonecrosis can occur in patients with sickle cell disease, which is typically identified on newborn screening and can present with anemia and vasoocclusive pain crises, not seen in this asymptomatic patient. (Choice D) Chronic kidney disease is a complication of chronic lead poisoning, a less common cause of anemia in young children. This child should have a routine lead screening test due to his age, but a presumed diagnosis of IDA is appropriate. Educational objective: Children with untreated iron deficiency anemia are at risk for psychomotor delay and long-term cognitive impairment. Therefore, universal screening should occur around age 1, and empiric iron supplementation is first-line treatment. References: Iron deficiency anemia in children. (http://www.ncbi.nlm.nih.gov/pubmed/25636824) Iron deficiency and other types of anemia in infants and children. (http://www.ncbi.nlm.nih.gov/pubmed/26926814)

Question 8

A 57-year-old woman comes to the primary care physician for a follow-up visit after undergoing a screening colonoscopy.  The colonoscopy revealed adenocarcinoma of the ascending colon and 2 well-differentiated, sessile, adenomatous polyps of the sigmoid colon.  The patient has a history of mitral valve prolapse and fibromyalgia.  She has also had a prior hysterectomy.  Her medications include hormone replacement therapy and ibuprofen.  The patient eats a high-fiber vegetarian diet and has consumed 3-4 alcoholic beverages per day for the past 30 years.  She smoked 1 pack of cigarettes a day for nearly 5 years, but quit 30 years ago.  There is no family history of cancer.  The patient is very concerned about being diagnosed with colon cancer.  Which of the following was her most significant risk factor for developing colon cancer?

Accepted Answer

Explanation: Risk factors for colorectal cancer (CRC) include family history, polyposis syndromes (eg, familial adenomatous polyposis), inflammatory bowel disease, and African-American race. Other risk factors include alcohol intake, cigarette smoking, and obesity. Several studies have suggested that even moderate alcohol intake (2-3 drinks/day) is associated with increased CRC risk, though the highest risk was seen in heavy drinkers (>4 drinks/day). Alcohol likely interferes with folate absorption, and heavy drinkers may also have decreased folate intake. Cigarette smoking is also associated with increased CRC risk, but the risk is primarily seen in current long-term smokers (eg, >30 years). This patient has a remote history of light tobacco use; her heavy alcohol intake was a more likely contributor to her risk for CRC (Choice E). (Choices B, C, and D) Regular nonsteroidal antiinflammatory drug intake, hormone replacement therapy in postmenopausal women, and a high-fiber diet that is rich in fruits and vegetables are all thought to offer some protection against developing CRC. Educational objective: Risk factors for colorectal cancer include family history, polyposis syndromes (eg, familial adenomatous polyposis), inflammatory bowel disease, and African-American race. Other risk factors include alcohol intake, cigarette smoking, and obesity. Protective factors include a high-fiber diet rich in fruits and vegetables, regular nonsteroidal antiinflammatory drug use, hormone replacement therapy, and regular exercise. References: Alcohol intake and colorectal cancer: a pooled analysis of 8 cohort studies. (http://www.ncbi.nlm.nih.gov/pubmed/15096331) Smoking and colorectal cancer: a meta-analysis. (http://www.ncbi.nlm.nih.gov/pubmed/19088354) Alcohol drinking and colorectal cancer risk: an overall and dose-response meta-analysis of published studies. (http://www.ncbi.nlm.nih.gov/pubmed/21307158)

Question 9

A 56-year-old man with a recent diagnosis of cirrhosis comes to the hospital for elective upper gastrointestinal endoscopy to evaluate for esophageal varices.  The patient has elevated liver aminotransferase levels, and a hepatitis serology was positive for chronic hepatitis C.  Abdominal imaging studies revealed mild ascites, a nodular-appearing liver, and splenomegaly.  He has no other medical problems.  The patient has a remote history of injection drug use and does not use tobacco or alcohol.  Vital signs are within normal limits.  Benzocaine throat spray is used for topical anesthesia, and procedural sedation is obtained with midazolam and fentanyl.  During the procedure, the patient's oxygen saturation by pulse oximetry gradually decreases to 85% on ambient air and does not improve with application of supplemental oxygen via face mask.  Physical examination demonstrates bluish discoloration of the lips and fingertips.  Lung fields are clear to auscultation, and heart sounds are normal.  Results of urgent laboratory tests are as follows:  Which of the following is the most likely cause of this patient's decrease in oxygen saturation?

Accepted Answer

Explanation: This patient has new-onset hypoxia by pulse oximetry (85%) during an endoscopic procedure, with a significant difference between the oxygen saturation value estimated on blood gas analysis and that obtained on pulse oximetry (ie, large oxygen saturation gap). He likely has acquired methemoglobinemia due to anesthetic use. Some medications - most commonly topical anesthetics (eg, benzocaine), dapsone, and nitrates (in infants) - cause the iron component of hemoglobin to be oxidized, thereby forming methemoglobin, which cannot bind oxygen. The remaining normal hemoglobin also has an increased affinity for oxygen, resulting in less oxygen delivery to tissues. Because methemoglobin absorbs light at distinct wavelengths, pulse oximetry commonly is ~85% (as seen in this patient) regardless of the true oxygen saturation. In parallel, blood gas analysis frequently returns a falsely elevated result for oxygen saturation (eg, 99% in this patient) as it provides an estimate based only on the PaO₂, not on effective hemoglobin-oxygen binding. These inaccurate readings create the large oxygen saturation gap. oxidized Cyanosis can occur when methemoglobin comprises ~10% of total hemoglobin, but hypoxia symptoms (eg, headache, lethargy) occur only when levels surpass 20%. At levels >50%, there is risk of severe symptoms (eg, altered mental status, seizures, respiratory depression) and death. Treatment involves discontinuing the causative agent and administering methylene blue, which helps reduce iron to its normal state. (Choice A) Anaphylaxis (eg, due to medication) can lead to respiratory compromise and hypoxia but is associated with symptoms such as wheezing, stridor, and dyspnea. (Choices C and G) Although atelectasis and mucus plugging can lead to transient hypoxemia due to a collapsed portion of lung, the hypoxemia is commonly reversible with supplemental oxygen and would not explain the oxygen saturation gap. Procedural hypoventilation should also correct with supplemental oxygen. (Choice D) This patient has clear lung fields and normal heart sounds, making pulmonary edema less likely. Pulmonary edema also typically improves with supplemental oxygen and is not characterized by a large oxygen saturation gap. (Choice E) Patients with liver disease can have large-volume ascites and severe muscle wasting, which may lead to decreased diaphragmatic excursion and resultant hypoxia. However, this patient has only mild ascites on ultrasound and no evidence of muscle wasting. (Choice F) Hepatopulmonary syndrome results from arteriovenous shunting in the lungs and can occur after years of liver disease. Patients frequently exhibit platypnea (induced dyspnea in the upright position) and orthodeoxia (hypoxia in the upright position). This syndrome would not explain the patient's large oxygen saturation gap. Educational objective: Acquired methemoglobinemia results from the oxidization of iron in hemoglobin, which is most commonly due to topical anesthetic agents or dapsone. It presents with hypoxia, a characteristic pulse oximetry reading of ~85%, and a large oxygen saturation gap. References: Methemoglobin--it's not just blue: a concise review. (http://www.ncbi.nlm.nih.gov/pubmed/16986127)

Question 10

A 5-year-old boy is brought to an urgent care center due to fatigue.  His mother says, "Normally, my son is running and jumping, but for the past week he has been resting on the couch and sleeping more than usual.  His eyes also look a bit yellow."  He has had no fevers, vomiting, or difficulty breathing.  A week ago, the patient had a skin infection that resolved after treatment with oral antibiotics.  Review of medical records shows a normal hemoglobin screening at his 1-year well-child visit.  Family history is significant for a maternal uncle who had several similar episodes of tiredness and jaundice.  Physical examination reveals a tired-appearing boy lying on the examination table watching television.  His neck is supple without lymphadenopathy, and scleral icterus and mild jaundice are present.  His cardiac and abdominal examinations are normal.  Laboratory results are as follows:  Peripheral blood smear is notable for red blood cell fragments and intracellular deposits of denatured hemoglobin.  Which of the following is the next best step in the diagnostic workup for this patient?

Accepted Answer

Explanation: 11ec2b69_c164_7823_8f63_b19ba7ee7eec_MD0005_00 Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked disorder most common in patients of Asian, African, or Middle Eastern descent. G6PD normally protects the red blood cells (RBCs) from oxidative stress by producing NADPH, an important cofactor in the pathway of oxidant inactivation. Deficiency of G6PD leads to intra- and extravascular hemolysis triggered by oxidative stress, such as infection, sulfa drugs, or fava beans. In this patient, the recent oral antibiotic was most likely trimethoprim-sulfamethoxazole, a sulfa drug. Clinical manifestations include jaundice and fatigue. Laboratory evidence of hemolysis includes anemia (normocytic, normochromic), indirect hyperbilirubinemia, low haptoglobin, and elevated lactate dehydrogenase. Peripheral smear shows characteristic bite cells and schistocytes (RBC fragments); Heinz bodies (accumulations of denatured hemoglobin) may be seen with special staining. bite cells A low G6PD assay, which detects NADPH formation, is diagnostic. This assay can be falsely negative if measured while the most severely G6PD-deficient RBCs are already hemolyzed; therefore, if the initial result is negative but there is strong suspicion for G6PD, the assay should be repeated after the acute episode. The acute hemolytic anemia typically self-resolves in 1-2 weeks after removal of the offending oxidant. Patients should be counseled on how to avoid common triggers. (Choice A) Bone marrow biopsy is indicated for suspicion of bone marrow suppression or failure, which typically presents with multiple cytopenias (eg, thrombocytopenia, leukopenia) and a low reticulocyte count. In contrast, this patient has isolated anemia and a compensatory reticulocytosis. (Choice B) Cold agglutinin titer is elevated in cold agglutinin-mediated autoimmune hemolytic anemia, which can also present with fatigue and anemia. However, symptoms typically develop after a viral infection, and a direct antiglobulin test would be positive. (Choice D) Hemoglobin electrophoresis detects hemoglobinopathies such as thalassemia and sickle cell disease. Anemia in thalassemia is microcytic, and patients with sickle cell anemia typically have pain crises starting in infancy and sickled RBCs on peripheral smear. This patient has a normocytic anemia with a characteristic peripheral smear of G6PD deficiency. (Choice E) Osmotic fragility testing is abnormal in hereditary spherocytosis, a genetic hemolytic anemia with spherocytes on peripheral smear and splenomegaly on examination, neither of which is seen in this patient. Educational objective: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked disorder in which acute hemolytic anemia is triggered by oxidative stress (eg, sulfa drug). Presentation includes jaundice and fatigue, and a G6PD assay is diagnostic. References: Congenital hemolytic anemia. (http://www.ncbi.nlm.nih.gov/pubmed/28189176)

Question 11

A 26-year-old woman, gravida 1 para 0, comes to the office to initiate prenatal care. The patient has had no nausea, abdominal pain, or vaginal bleeding since her last menstrual period 8 weeks ago. She has no chronic medical conditions. She had an appendectomy as a child but no other surgery. The patient takes a daily prenatal vitamin and does not use tobacco, alcohol, or illicit drugs. She is a vegetarian and emigrated from Southeast Asia 5 years ago. Blood pressure is 110/75 mm Hg and pulse is 80/min. BMI is 21 kg/m². Pelvic examination reveals an 8-week-sized, nontender uterus and no adnexal masses or tenderness. Laboratory results are as follows: A transvaginal ultrasound reveals an 8-week intrauterine gestation with a normal heartbeat. Which of the following is the most likely cause of this patient's anemia? A)Folate deficiency B)Glucose-6-phosphate dehydrogenase deficiency C)Iron deficiency D)Physiologic anemia of pregnancy E)Thalassemia trait

Accepted Answer

The answer of A 26-year-old woman, gravida 1 para 0,...

Question 12

A 16-month-old full-term girl is brought to the office to establish well-child care.  The patient's family recently moved to the area and they have no concerns about her development.  The patient weaned from breastfeeding at age 12 months, and her current diet mainly consists of whole cow's milk.  She has no chronic medical conditions and takes no medications.  She was born to a 24-year-old primigravida Greek woman and a 30-year-old African American man.  The patient's father has sickle cell trait and her first cousin has sickle cell anemia; maternal family history is noncontributory.  Physical examination reveals pallor of the conjunctivae but is otherwise unremarkable.  Laboratory results are as follows:  Hemoglobin electrophoresis reveals 40% HbS and 60% HbA.  Which of the following is the most likely cause of this patient's anemia?

Accepted Answer

Explanation: 11ec2b69_c165_8996_8f63_9b6fd3574731_MD0005_00 This patient's anemia is most likely caused by iron deficiency. In children age >1, excessive milk intake (>24 oz/day) and low intake of iron-rich foods (eg, meats, cereals) contribute to the development of iron deficiency anemia. Given the high prevalence of iron deficiency in children age <2, these findings are sufficient to begin an empiric trial of iron supplementation. Iron deficiency is typically diagnosed based on clinical history and low hemoglobin. However, in patients with a family history of hemoglobinopathy (eg, sickle cell anemia), hemoglobin electrophoresis must be ordered. The presence of HbA and HbS in a 60:40 ratio, respectively, is consistent with sickle cell trait, which is generally asymptomatic and not a cause of anemia and microcytosis. This patient's microcytic anemia (low mean corpuscular volume) with an elevated red cell distribution width is most likely due to iron deficiency anemia. (Choice A) Alpha thalassemias are characterized by the presence of Hb Barts (4 gamma chains) on electrophoresis, not seen in this patient. (Choice B) Anemia of chronic disease is a normocytic, normochromic anemia that occurs in patients with chronic medical conditions (eg, renal failure, rheumatoid arthritis). (Choice C) Beta thalassemias are due to mutations in the beta globin genes; they are not associated with the presence of HbS. Sickle-beta thalassemia is comprised predominantly of HbS with <30% HbA. HbF and HbA2 are also typically elevated. (Choice D) HbSC is a less-severe variant of sickle cell disease characterized by a mild normocytic anemia. Hemoglobin electrophoresis showing almost equal amounts of HbS and HbC is diagnostic. Educational objective: Iron deficiency, commonly caused by excessive milk intake and insufficient iron-rich foods in young children, results in a microcytic anemia with an elevated red cell distribution width. The presence of HbA and HbS in a 60:40 ratio, respectively, on hemoglobin electrophoresis is consistent with sickle cell trait, which is asymptomatic and does not cause anemia. References: Iron deficiency and other types of anemia in infants and children. (http://www.ncbi.nlm.nih.gov/pubmed/26926814) Evaluation of anemia in children. (http://www.ncbi.nlm.nih.gov/pubmed/20540485)

Question 13

A 53-year-old woman comes to the emergency department with a 1-day history of hematemesis and hypotension.  She was hospitalized for unprovoked right femoral vein thrombosis and pulmonary embolism 1 month ago and has been taking warfarin since.  In the emergency department, the patient is resuscitated with intravenous fluids and fresh frozen plasma.  Warfarin is discontinued and she is started on intravenous pantoprazole.  Upper gastrointestinal endoscopy shows several deep gastric ulcers.  Later during the hospital course, the option of inferior vena cava (IVC) filter placement is discussed with the patient.  Which of the following complications would this patient be at highest long-term risk for developing following IVC filter placement?

Accepted Answer

Explanation: Inferior vena cava (IVC) filters are an option for patients with acute deep venous thrombosis (DVT) who have contraindications to anticoagulation (eg, recent surgery, hemorrhagic stroke, bleeding diathesis, active bleeding). IVC filters can be permanent or retrievable and are usually placed via a transvenous approach. They inhibit progression of lower extremity clots through the IVC toward the lungs. Acute complications of IVC filter placement include guidewire entrapment within the filter and post-procedural complications (eg, acute insertion site thrombosis, hematoma, arteriovenous fistula). The main long-term complication of IVC filter placement is recurrent DVTs. The filter can prevent clot progression to a pulmonary embolism, but it does not prevent future DVTs or treat the underlying thrombotic predisposition. As a result, patients can develop both acute and recurrent thrombosis at the insertion site. IVC thrombosis can also occur due to thrombogenicity of the filter, new local thrombus formation, or trapped embolus. IVC filters do not appear to affect overall mortality significantly. (Choice A) IVC filter migration and perforation through the IVC are much less common complications than recurrent DVT. (Choice B) IVC filters are usually placed in the IVC just below the renal veins to decrease risk of venous thromboembolism from all likely venous pathways. The portal vein drains into the liver above this level and would be unlikely to be affected by an IVC filter. (Choice D) Small thrombi can extend through the IVC filter or go through collateral circulation, but most studies have shown that recurrent pulmonary thromboembolism is an uncommon complication of IVC filters. (Choice E) Retroperitoneal bleeding is most commonly due to trauma to the lower back, vascular procedures near the retroperitoneal space (eg, cardiac catheterization, aortic catheter), anticoagulation, or hemorrhage from a malignancy in the retroperitoneal organs (eg, pancreas). However, retroperitoneal bleeding is not a common complication of IVC filter placement. Educational objective: Inferior vena cava (IVC) filters are an option for patients with acute deep venous thrombosis (DVT) who have contraindications to anticoagulation. Long-term complications of IVC filter placement include recurrent DVTs and IVC thrombosis. IVC filters do not appear to affect overall mortality significantly. References: Vena caval filters: current knowledge, uncertainties and practical approaches (http://www.ncbi.nlm.nih.gov/pubmed/19550322) Eight-year follow-up of patients with permanent vena cava filters in the prevention of pulmonary embolism: the PREPIC (Prevention du Risque d'Embolie Pulmonaire par Interruption Cave) randomized study. (http://www.ncbi.nlm.nih.gov/pubmed/16009794)

Question 14

A 36-year-old Caucasian female is seen in the emergency department (ED) for the evaluation of a sudden onset, left lower chest pain and difficulty in breathing.  Approximately one year ago, she was diagnosed with left lower extremity deep vein thrombosis secondary to smoking and oral contraceptive pill (OCP) use.  At that time, her OCPs were discontinued, she quit smoking, and she was treated with six months of warfarin therapy.  She does not have any other medical problems.  Her mother and maternal aunt have had "problems with blood clots."  After performing the appropriate ancillary procedures, results reveal the presence of multiple, left-sided pulmonary emboli.  A diagnosis of an inherited thrombophilia is suspected.  Which of the following is most likely to be present in this patient?

Accepted Answer

Explanation: The patient in the above scenario has suffered from a second episode of venous thromboembolism in a year. Factor V Leiden is the most common cause of inherited or heredity thrombophilia, accounting for approximately 40-50% of the inherited thrombophilias. These disorders predispose the patient to the development of venous thromboembolism. (Choices B, C, D and E)Other common causes of heredity thrombophilia include prothrombin gene mutation, hyperhomocysteinemia, protein C, protein S, and antithrombin III deficiency. Some patients may have more than one type of inherited disorder, and are at even greater risk for venous thromboembolism. Educational Objective: Factor V Leiden is the most common cause of inherited or heredity thrombophilia, accounting for approximately 40-50% of the inherited thrombophilias.

Question 15

A 55-year-old Caucasian male presents to your office complaining of easy fatigability.  He used to be physically active and always preferred to walk to work, which is five blocks away from where he lives.  Now he says, "Doc, I get short of breath when I walk even two blocks."  He denies any palpitations, chest pain, cough, or lower extremity swelling.  He does not feel down and has no problems with sleep.  His past medical history is insignificant.  He is currently not taking any medications.  His blood pressure is 120/70 mm Hg and heart rate is 95/min.  The physical examination is significant for pallor of the conjunctivae and oral mucosa.  His laboratory values are:  Blood smear analysis shows microcytic erythrocytes with anisocytosis.  What is the best next step in the management of this patient?

Accepted Answer

Explanation: The diagnosis of iron deficiency anemia may not seem straightforward in this patient. Although microcytic/hypochromic anemia with anisocytosis is consistent with iron deficiency anemia, the serum ferritin value could be considered troublesome because the traditional ferritin cutoff point for iron deficiency is 15 ng/mL. Almost all patients with serum ferritin concentrations <15 ng/mL are iron deficient. There is no other clinical situation that explains such an extremely low level of serum ferritin. With the use of a 15 ng/mL cutoff point, the sensitivity of serum ferritin for detecting iron deficiency is 59% and specificity is 99%. However, since the sensitivity of serum ferritin is only 59% with this cutoff, a significant number of patients may have a value which is "borderline low" from 15-30 ng/mL; therefore, a value >15 ng/mL does not exclude the diagnosis. In fact, the sensitivity of serum ferritin rises to 92% when 30 ng/mL is used as the cutoff, and specificity remains similar. One, therefore, needs to be aware that the traditional cutoff of 15 ng/mL for diagnosing iron deficiency anemia is not an absolute. Iron deficiency anemia is not excluded by the ferritin level of 24 ng/mL in this patient; in fact, iron deficiency is the most likely diagnosis given the clinical scenario. The gastrointestinal tract is the major source of blood loss leading to iron deficiency anemia in males; therefore, a fecal occult blood test is a reasonable initial choice for this patient. A series of three fecal occult blood tests helps to maximize the sensitivity of the test, although endoscopy would likely be needed even if negative. Colonoscopy is typically performed before EGD in these patients unless there is a particular reason to suspect an upper gastrointestinal source of bleeding, such as NSAID use. (Choice A) Autoimmune hemolytic anemia is usually normocytic/normochromic. (Choice C) Although thalassemias can manifest as microcytic anemia, these usually present earlier in life, and characteristic findings on the blood smear may be observed ("target cells"). (Choice D) Rheumatoid arthritis causes chronic inflammation and is a common cause of anemia of chronic disease. However, the serum ferritin level is typically normal to elevated in anemia of chronic disease since it is an acute-phase reactant. (Choice E) Vitamin B12 and folate deficiency anemias are usually macrocytic. Educational objective: Almost all patients with serum ferritin concentrations of less than the traditional cutoff of 15 ng/mL are iron deficient. However, the sensitivity using this cutoff is only modest at best and it cannot be used to exclude the diagnosis of iron deficiency since the majority of patients with a level of 15-30 mg/nL are also iron deficient. The gastrointestinal tract is the major source of blood loss leading to iron deficiency anemia in males.

Question 16

A 53-year-old man complains of acute onset of vomiting during a Caribbean cruise.  He has had multiple episodes of vomiting since the morning and feels "dehydrated."  The patient also reports an episode of watery diarrhea, mild headache, and muscle pains.  His temperature is 38.1 C (100.6 F) and the remainder of the physical examination is unremarkable. He traveled to Mexico for business a month ago.  Ten other passengers on the cruise report similar symptoms.  Stool cultures are negative.  Which of the following is the most likely cause of this patient's condition?

Accepted Answer

Explanation: 11ec2b69_c16a_dfd1_8f63_d1b4b73abaf1_MD0005_00 This patient presents with vomiting-predominant gastroenteritis and negative stool culture, which are suggestive of norovirus. Norovirus is the most common cause of epidemic gastroenteritis and is now the most common cause of all gastroenteritis in adults and children. Norovirus is spread via fecal-oral contamination, and the virus can be transmitted from food and water, fomites, or airborne droplets from vomitus. Norovirus outbreaks are common and occur in institutionalized settings such as nursing homes and health care facilities, in addition to restaurants and cruise ships. Norovirus can cause the following: Asymptomatic infection Fever with watery diarrhea - noninflammatory small-bowel process Severe illness - fever, vomiting, headache, and other systemic symptoms Symptoms usually start suddenly and last 48-72 hours. Diagnosis is generally clinical, and most patients improve with supportive care. If needed, diagnosis can be confirmed by polymerase chain reaction or nucleic acid-based testing. (Choice A) Campylobacter infection most commonly presents with acute onset of cramping abdominal pain and inflammatory diarrhea (eg, mucus, blood). Diagnosis is by stool culture. (Choice B) Clostridium perfringens is typically associated with traumatic gas gangrene but is also an important cause of watery diarrhea. The spores of C perfringens germinate in warm food; once ingested, the bacteria produce a toxin in the gastrointestinal tract that causes disease. Fever and vomiting are uncommon. (Choice C) Enterotoxigenic Escherichia coli is the most common causative agent of travelers' diarrhea, but is much less frequently a cause of diarrhea in outbreaks. It classically presents with malaise, anorexia, and abdominal cramps, followed by the acute onset of watery diarrhea. (Choice D) Listeria monocytogenes is a rare cause of epidemic gastroenteritis (usually associated with deli meats and soft cheeses). In addition to watery diarrhea, fever, and nausea/vomiting, L monocytogenes gastroenteritis may also present with non-gastrointestinal symptoms such as myalgia, arthralgia, and headache. Diagnosis can be confirmed from special stool culture media. Educational objective: Norovirus is the most common cause of gastroenteritis, including epidemic gastroenteritis, in adults and children. Vomiting is more prominent. Outbreaks are common and occur in restaurant, travel, and health care settings. References: Norovirus gastroenteritis. (http://www.ncbi.nlm.nih.gov/pubmed/19864676) Acute gastroenteritis surveillance through the National Outbreak Reporting System, United States. (http://www.ncbi.nlm.nih.gov/pubmed/23876187)

Question 17

A 60-year-old man has experienced progressive shortness of breath over the last 6 months that is occasionally accompanied by chest pain.  He was diagnosed with hypertension 10 years ago.  Twenty years ago, he suffered from advanced-stage Hodgkin lymphoma that was treated with combination chemotherapy and radiation therapy.  He is a lifetime nonsmoker.  Blood pressure is 138/90 mm Hg and pulse is 78/min and regular.  Physical examination shows a 2/4 early diastolic murmur at the left sternal border.  Echocardiogram shows an enlarged left atrium, a normal-size left ventricle with an ejection fraction of 60%, and moderate diastolic dysfunction.  Both the mitral and aortic valves appear sclerotic and calcified.  The aortic root is normal-size but is echo bright.  There is moderate aortic regurgitation.  Cardiac catheterization shows ostial narrowing of the right and left main coronary arteries.  Which of the following is the most likely diagnosis?

Accepted Answer

Explanation: This patient most likely has radiation-induced cardiotoxicity. Long-term survivors of Hodgkin lymphoma are at risk of developing cardiovascular complications due to chemotherapy and/or radiation therapy. Radiation therapy causes diffuse fibrosis in the interstitium of the myocardium, along with progressive fibrosis of the pericardial layers, cells in the conduction system, and the cusps and/or leaflets of the valves. It also causes injury to the intimal layer, with arterial narrowing typically involving the ostial parts of coronary vessels. These effects lead to: Myocardial ischemia and/or infarction Restrictive cardiomyopathy with diastolic dysfunction Constrictive pericarditis Valvular abnormalities (mitral or aortic stenosis/regurgitation) Conduction defects (sick sinus syndrome or variable degrees of heart block) (Choice A) The anthracycline class of drugs causes a dose-dependent decline in the ejection fraction, leading to dilated cardiomyopathy. It is not associated with valvular disease or coronary artery disease. (Choice B) Chronic severe hypertension can lead to left ventricular hypertrophy with diastolic dysfunction; however, it is not associated with sclerosis/calcification of valves or ostial narrowing of the coronary arteries. (Choice D) Rheumatic heart disease causes progressive sclerosis of the mitral and/or aortic valve, causing mitral stenosis/regurgitation or aortic stenosis/regurgitation. The additional associated findings - diastolic dysfunction, echogenic aortic root, and ostial narrowing of the coronary arteries - are more consistent with radiation-induced cardiotoxicity. (Choice E) Secondary malignancy (eg, breast, lung or gastrointestinal cancer; acute leukemia, non-Hodgkin lymphoma) is the leading cause of death in survivors of Hodgkin lymphoma. There are no clinical findings suggesting a secondary malignancy in this patient. Educational objective: Clinical manifestations of radiation-induced cardiotoxicity include coronary disease with myocardial ischemia and/or infarction, restrictive cardiomyopathy with diastolic dysfunction, pericardial disease, valvular abnormalities, and/or conduction defects. References: Cardiac complications of oncologic therapy. (http://www.ncbi.nlm.nih.gov/pubmed/24108563) Clinically significant cardiac disease in patients with Hodgkin lymphoma treated with mediastinal irradiation. (http://www.ncbi.nlm.nih.gov/pubmed/20858859)

Question 18

A 15-month-old boy is brought to the clinic due to fatigue.  His father states that the patient used to nap for 2 hours in the afternoon but for the last 2 weeks has taken a 2-hour nap in the morning as well.  The child is a picky eater and drinks 960 mL (32 oz) of cow's milk each day.  He takes no daily medications, and his immunizations are up to date.  Physical examination reveals a tired-appearing boy.  Conjunctivae are pale and anicteric.  Cardiac examination reveals normal heart tones.  The abdomen is soft with no hepatomegaly.  Capillary refill is <2 seconds; nail beds have pallor.  Hemoglobin is 8.1 g/dL, and a capillary lead level is undetectable.  A presumptive diagnosis of iron deficiency anemia is made.  The boy is prescribed ferrous sulfate, which he takes with orange juice between meals.  His cow's milk intake is restricted to 480 mL (16 oz) per day.  Which of the following changes is expected to occur first in response to treatment?

Accepted Answer

Explanation: 11ec2b69_c167_103a_8f63_178a8e0a86d8_MD0005_00 Iron deficiency is the most common nutritional deficiency in children and should be suspected in any child drinking >24 oz of cow's milk per day. Fatigue and pallor may occur, but patients are often asymptomatic and detected on universal screen around age 1. Given the high prevalence of iron deficiency anemia in infants and toddlers, a presumptive diagnosis of iron deficiency is made when hemoglobin <11 g/dL. Lead level should also be measured, but additional studies are usually not needed in the initial workup. An empiric trial of ferrous sulfate is considered the most cost-effective treatment, and the doses should be given with juice between meals as vitamin C facilitates iron absorption. Patients should also be advised to limit milk intake to <20 oz per day and to increase intake of iron-rich foods (eg, meats, fortified cereals). Patients with iron deficiency have hypochromic, microcytic red blood cells (RBCs) and decreased reticulocytes as the bone marrow is unable to produce the requisite number of RBCs without adequate iron substrate. Within 1-2 weeks of initiating supplementation, the reticulocyte count increases quickly. However, in patients with moderate to severe iron deficiency, it usually takes about a month for the hematocrit and hemoglobin to increase and a few months to return to regular levels (Choices B and C). Therefore, after a month of empiric iron supplementation, an increase in hemoglobin ≥1 g/dL supports the diagnosis of iron deficiency anemia. Ferrous sulfate should be maintained for 2-3 months after hemoglobin normalization to replenish iron stores. (Choice A) Ferritin reflects iron stores and does not begin to rise until after hemoglobin normalizes. (Choice D) The Mentzer index refers to the ratio of mean corpuscular volume (MCV) to total RBC count. Before treatment, patients with iron deficiency anemia generally have low MCV and total RBC counts with a high Mentzer index of >13. Educational objective: Children with presumed iron deficiency anemia due to poor diet are treated with an empiric trial of iron supplementation. Iron therapy increases reticulocyte production followed by an increase in hematocrit and hemoglobin in approximately 1 month. References: Diagnosis and prevention of iron deficiency and iron-deficiency anemia in infants and young children (0-3 years of age). (http://www.ncbi.nlm.nih.gov/pubmed/20923825) Evaluation of anemia in children. (http://www.ncbi.nlm.nih.gov/pubmed/20540485)

Question 19

A 62-year-old Caucasian man comes to the office with complaints of a dull, non-throbbing headache, hearing loss on the left side, and persistent tinnitus.  His symptoms have been getting progressively worse for the last two weeks.  He has a history of small cell cancer of the lung, which was treated with a combination of chemotherapy and radiotherapy four months ago.  His lung mass has reduced considerably in size after its treatment.  A contrast-enhanced magnetic resonance imaging scan shows a 1 x 2 cm circumscribed mass in the left cerebellopontine angle compressing the eighth cranial nerve.  There is another small 0.5 x 1 cm mass in the left frontal lobe cortex with significant edema surrounding the lesion.  Which of the following is the most likely cause of this patient's symptoms?

Accepted Answer

Explanation: Brain tumors are classified into tumors that originate in the brain itself (primary brain tumor), and those that originate elsewhere in the body and metastasize to the brain from another primary site (secondary brain tumor). Secondary brain tumors are the more common type of brain tumors. The common primary sites of origin of brain metastasis, in the order of frequency, are: lung, breast, unknown primary, melanoma, and colon cancer. Small cell lung cancer has a predilection for early metastasis to the brain. The most common route of spread of the cancer is by hematogenous spread. The diagnostic imaging of choice to evaluate a patient with suspected metastatic disease is a contrast-enhanced MRI scan. The clues to the presence of a metastatic brain lesion (as compared to a primary brain tumor) on radiographic imaging are the presence of multiple, well-circumscribed lesions, and a relatively large amount of vasogenic edema as compared to the size of the lesion. In the above vignette, the patient's symptoms is most likely being caused by a metastatic lung cancer which has compressed the eighth cranial nerve. Educational Objective: Metastatic lesions to the brain are the most common cause of brain tumors. These account for more than half of all the brain tumors seen in adult patients.

Question 20

A 54-year-old woman is admitted to an outpatient surgical center for arthroplasty of the right knee.  She is a former professional tennis player and has struggled with pain and stiffness in her knee for many years after multiple meniscal injuries in her early 30s.  She is married to an attorney who has been very involved in her care but has frequently questioned the decision-making of her physicians.  In the operating room, the surgeon performs a "time-out" procedure to confirm the details of the surgery.  He announces that he will operate on the left knee, which is confirmed by the anesthesiologist.  The surgical nurse double checks the patient's chart and corrects the surgeon that the operation is for the right knee, not the left.  The surgeon notes this error and proceeds to perform the procedure on the correct side.  Which of the following actions should be taken in response to this error?

Accepted Answer

Explanation: This scenario is characterized as a "near-miss event," a type of medical error which, as a result of timely intervention or simply circumstance, did not reach the patient and no harm occurred. For approximately every 300 near misses, 1 adverse outcome occurs, indicating that analysis of near-miss events can be helpful in improving overall patient safety. For this reason, near-miss events should be reported to administration to ensure that adequate measures are taken to prevent other practitioners from making the same error. Disclosure to the patient should be determined on a case-by-case basis by the individual practitioner. In general, disclosure is recommended if there is a related, ongoing safety threat to the patient (potential for harm) or if the patient is aware of the near miss and disclosure will decrease anxiety and improve trust. (Choice A) Although there was no harm to the patient, the incident should be reported to hospital administration for analysis and prevention of similar potential errors. (Choices B and C) Disclosure to the patient and/or her husband is not mandatory. However, if the patient is aware of a near miss or if there is any potential for further harm, disclosure is advisable to preserve the physician-patient relationship. (Choice E) A sentinel event is any unanticipated event in a health care setting that results in death or serious physical or psychological injury. Examples include in-hospital suicide, abduction, discharge of an infant to the wrong family, or surgery performed on the wrong site or person. Although not all sentinel events result from medical errors, it is important for hospital administration to examine whether they could have been prevented to ensure future patient safety. Educational objective: Near-miss events involve medical errors that are caught before they reach the patient, causing no harm. Reporting of near-miss events is crucial in preventing more dangerous outcomes in the future, including events that cause death or serious injury.

Exam 2: Foundations of Independent Practice