A 61-year-old man comes to the office for evaluation of urinary symptoms. Review of systems is positive for nocturnal urinary frequency, occasional dribbling, and a weak urinary stream for the past 3 months. The patient was diagnosed with type 2 diabetes mellitus 16 years ago. Other medical conditions include hypertension, myocardial infarction 2 years ago, and moderately decreased visual acuity. Blood pressure is 160/100 mm Hg and pulse is 60/min. Examination shows a left-sided carotid bruit and trace bilateral ankle edema. Postvoid bladder residual volume is 40 mL. Dipstick urinalysis reveals 2+ protein and no blood. Serum creatinine level is 2.1 mg/dL. Hemoglobin A1c is 7.3%. Which of the following is the most likely cause of this patient's chronic kidney disease?

Question

A 61-year-old man comes to the office for evaluation of urinary symptoms.  Review of systems is positive for nocturnal urinary frequency, occasional dribbling, and a weak urinary stream for the past 3 months.  The patient was diagnosed with type 2 diabetes mellitus 16 years ago.  Other medical conditions include hypertension, myocardial infarction 2 years ago, and moderately decreased visual acuity.  Blood pressure is 160/100 mm Hg and pulse is 60/min.  Examination shows a left-sided carotid bruit and trace bilateral ankle edema.  Postvoid bladder residual volume is 40 mL.  Dipstick urinalysis reveals 2+ protein and no blood.  Serum creatinine level is 2.1 mg/dL.  Hemoglobin A1c is 7.3%.  Which of the following is the most likely cause of this patient's chronic kidney disease?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d4da_3623_bc81_1d7db88ca994_MD0003_00 This patient's age, nocturia, dribbling, and weak urinary stream initially suggest benign prostatic hyperplasia (BPH). However, laboratory evaluation shows proteinuria and elevated creatinine, which are unexpected with BPH alone. Given his long-standing diabetes mellitus, these findings make diabetic kidney disease (DKD) the most likely cause. DKD is a microvascular process (microangiopathy) that predominantly affects glomeruli. It is commonly asymptomatic in early stages but found on routine studies. This patient's risk factors include: long-standing diabetes mellitus (eg, >5-10 years). evidence of another microvascular disease (eg, retinopathy suggested by decreased visual acuity). poor glycemic control (ie, A1c >7.0%; higher levels recommended only for patients who are elderly or have increased risk for hypoglycemia). poorly controlled hypertension (>130/80 mm Hg). Proteinuria (reflecting glomerular damage), particularly if persistent, is an important clue for diagnosis. Although a positive urine dipstick test revealed this patient's proteinuria, the preferred screening test is the random urine albumin/creatinine ratio, which detects excess albuminuria earlier. Proteinuria is associated with increased risk for cardiovascular mortality and concurrent macrovascular disease (cardiovascular disease), like that in this patient (eg, carotid bruit, myocardial infarction). (Choice B) Minimal change disease (MCD) causes nephrotic syndrome (proteinuria >3.5 g/day, edema, hyperlipidemia) due to podocyte damage. However, 2+ proteinuria on urine dipstick is unlikely to represent nephrotic-range proteinuria. MCD is more common in children. Although nephrotic syndrome can occur in diabetes mellitus, it usually involves glomerular (eg, glomerulosclerosis) rather than podocyte damage. urine dipstick (Choice C) Neurogenic bladder can cause urinary symptoms but typically results from spinal cord injury or multiple sclerosis, is often accompanied by bladder spasms, and would not cause elevated creatinine or proteinuria. Diabetic autonomic neuropathy can affect the bladder but causes overflow incontinence (continuous dribbling) with high postvoid residuals; this would not explain proteinuria or elevated creatinine. (Choice D) BPH explains this patient's urinary symptoms and increases the risk for obstructive uropathy (ie, urinary outflow tract obstruction), but postvoid residual <50 mL is inconsistent with significant obstruction. In addition, BPH is not associated with proteinuria and does not cause elevated creatinine unless complete obstruction occurs. (Choice E) Renal papillary necrosis is a complication of sickle cell nephropathy, analgesic use, and diabetes mellitus. It typically causes flank pain and hematuria. Educational objective: Diabetic kidney disease, a microangiopathic glomerular process suggested by persistent proteinuria, more likely occurs in long-standing diabetes mellitus, suboptimal glycemic and blood pressure control, and other systemic microvascular damage (eg, retinopathy). It is associated with increased risk for cardiovascular mortality. References: Albuminuria changes and cardiovascular and renal outcomes in type 1 diabetes: the DCCT/EDIC study. (http://www.ncbi.nlm.nih.gov/pubmed/27797889)

A 61-Year-Old Man Comes to the Office for Evaluation of Urinary