USMLE-Rx Step 2 Qmax Challenge #21569

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

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A 1-month-old girl presents to the emergency department with emesis. She was feeding well on breast milk until 1 week ago, when she began to have nonbilious emesis immediately after feeding. The episodes have progressed, and are now occurring after every meal with nonbilious projectile emesis. Her parents are surprised that the patient attempts to feed soon after every episode of emesis. They think she has become less active and has lost weight. Her temperature is 36.8°C (98.2°F), respiratory rate is 30/min, heart rate is 160/min, and blood pressure is 88/55 mm Hg. Her abdomen is nondistended and mildly tender diffusely. There is a palpable, mobile, olive-shaped mass in the mid-epigastric region. Ultrasound imaging of the abdomen is shown in the image.

Laboratory evaluation is most likely to show which of the following?

A. Conjugated hyperbilirubinemia
B. High serum amylase and lipase levels
C. Hyperkalemia
D. Hypochloremic metabolic alkalosis
E. Metabolic acidosis

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This practice question is an actual question from the USMLE-Rx Step 2 CK test bank. Get more Step 2 CK study help at USMLE-Rx.com.