USMLE-Rx Step 2 Qmax Challenge #21656

Check out today’s Step 2 CK Qmax Question Challenge.

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A 5-year-old boy is brought to the pediatrician because of persistent hypercalciuria discovered on routine urinalysis. The boy has a history of renal stones and Ehlers-Danlos syndrome. His family history is notable for a sister, 22 years old, who was diagnosed with Ehlers-Danlos syndrome as a child. The boy is examined and is in no distress. He is in the 5th percentile for height and the 10th percentile for weight. His respiratory rate is 30/min, heart rate is 100/min, and blood pressure is 110/70 mm Hg. The boy has a soft late-systolic murmur that is heard best at the apex. His lungs are clear and abdomen is soft. His lower extremities are notable for laxity of his knee joint. Laboratory studies show:

Na+: 140 mEq/L
K+: 2.6 mEq/L
Cl-: 119 mEq/L
HCO3-: 9 mEq/L
Blood urea nitrogen: 8 mg/L
Creatinine: 0.5 mg/L

Arterial blood gas analysis reveals a pH of 7.2.
What is the most appropriate treatment for this boy’s renal disorder?

A. Acetazolamide
B. Ammonium chloride
C. Potassium citrate
D. Sodium polystyrene sulfonate
E. Vitamin D


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