Wednesday, November 15, 2017

Repeated USMLE Questions Step 1- 197

A 20-year-old exchange male student from Greece presents to the office for evaluation of glucose-6-phosphate dehydrogenase deficiency. Two days ago, he noticed yellow discoloration of his conjunctiva. His family history is significant for hemolytic anemia due to glucose-6-phosphate dehydrogenase deficiency. Which of these conditions is most likely associated with hemolytic anemia?

A-Increased plasma unconjugated bilirubin

B-Increased bilirubin in urine

C-Increased urobilinogen in urine

D-Clay colored stool

E-Dark brown urine


Hemolysis of RBCs results in a large amount of bilirubin delivered to the liver. The ability of the liver to conjugate all the bilirubin to glucuronic acid fails and unconjugated bilirubin increases in the plasma causing jaundice. Unconjugated bilirubin is unlikely to pass into the urine because it is bound to albumin and has low solubility in plasma. Clay colored stool occurs due to absence of bile pigments in the colon, which is not associated with hemolytic anemia.

The correct answer is A

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