Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.
A 45-year-old man is evaluated during an annual routine health maintenance visit. History is notable for type 2 diabetes mellitus (diet controlled) diagnosed 3 months ago. Family history is significant for his father who developed end-stage kidney disease due to diabetes at age 68 years. He reports no symptoms and takes no medications.
On physical examination, temperature is 37.0 °C (98.6 °F), blood pressure is 135/78 mm Hg, pulse rate is 70/min, and respiration rate is 12/min. BMI is 31. Cardiac examination reveals no murmur or gallop. The lungs are clear. There is 1+ peripheral edema.
Laboratory studies show a serum creatinine level of 1.0 mg/dL (88.4 µmol/L).
Which of the following is the most appropriate next step in management?
A. Measure urine albumin excretion
B. Order kidney ultrasonography
C. Perform dipstick urinalysis
D. Start an angiotensin receptor blocker
MKSAP Answer and Critique
The correct answer is: A. Measure urine albumin excretion.
Urine albumin excretion measurement is appropriate for this patient with risk factors for chronic kidney disease (CKD). Patients with diabetes mellitus are at a markedly increased risk of CKD, and treatment of patients with diabetes and moderately increased albuminuria (formerly known as microalbuminuria) using angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) can reduce the risk of progression to overt nephropathy. Moreover, determining the level of albuminuria and estimated glomerular filtration rate is important for detecting the presence of CKD and accurately staging CKD if present. CKD staging has important implications with regard to clinical prognosis. Guidelines differ among several medical organizations regarding the optimal approach to CKD screening. Whereas the American College of Physicians guidelines state that there is insufficient evidence to support or discourage screening for CKD in persons with CKD risk factors such as diabetes, the National Kidney Foundation and the American Diabetes Association support screening for kidney disease in all patients with diabetes.
There is no evidence to support the value of kidney ultrasonography in persons who have no clinical evidence of kidney disease and no family history of genetic kidney disease such as autosomal dominant polycystic kidney disease.
Dipstick urinalysis is not sufficiently sensitive to detect the presence of moderately increased albuminuria; the results are semiquantitative, and estimations of proteinuria can be significantly affected by urine concentration.
Although ARBs have been demonstrated to reduce the risk of progression from moderately increased albuminuria to overt diabetic nephropathy, no studies have demonstrated a beneficial effect of these medications in patients who do not have increased urine albumin excretion or existing hypertension. It remains unknown whether ARBs or ACE inhibitors are protective in patients with moderately increased albuminuria due to etiologies other than diabetic nephropathy.
Key Point
- Patients with risk factors for chronic kidney disease should be screened using laboratory studies, most commonly determining the estimated glomerular filtration rate and urine testing for protein or albumin.
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