Hepatobiliary Disease USMLE Step 1 Practice Question
A 3-day-old male newborn presents with severe jaundice and lethargy. Vital signs show HR 145/min, RR 48/min, temperature 37.2°C. Laboratory studies reveal unconjugated hyperbilirubinemia at 18 mg/dL with normal hemoglobin (14 g/dL), normal reticulocyte count, and negative direct antiglobulin test. Abdominal ultrasound shows no hepatomegaly or biliary obstruction. The infant has not received prophylactic vitamin K. Which enzyme deficiency most likely explains these findings?
Answer choices
- AAlanine aminotransferase deficiency
- BAlkaline phosphatase deficiency
- COrnithine transcarbamylase deficiency
- DUDP-glucuronosyltransferase deficiencyCorrect answer
- EGlucose-6-phosphatase deficiency
- FBilirubin oxidase deficiency
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