10 free USMLE Step 1 practice questions in the real exam format, covering the official content areas, with an explanation for every answer.
USMLE Step 1 Practice Test 5Tutor mode
Question 1 of 10
Reproductive & Endocrine Systems
A 10-day-old newborn is brought to the emergency department because of vomiting, poor feeding, and lethargy for 2 days. At birth, the newborn was noted to have an enlarged clitoris and partially fused labioscrotal folds; karyotype is 46,XX. Pulse is 184/min, and blood pressure is 58/30 mm Hg. Examination shows dry mucous membranes and decreased skin turgor. Serum studies show a sodium concentration of 124 mEq/L, potassium concentration of 6.8 mEq/L, and glucose concentration of 48 mg/dL. The serum concentration of which of the following is most likely increased in this patient?