Lipid Biochemistry USMLE Step 1 Practice Question
A 56-year-old woman with primary biliary cholangitis presents with progressive jaundice and pruritus. Vital signs: BP 128/82, HR 88, RR 16, Temp 37°C, SpO2 98%. Laboratory studies reveal elevated total cholesterol (320 mg/dL), normal LDL-C, elevated unesterified cholesterol, and lipoprotein-X (Lp-X) on serum electrophoresis. Alkaline phosphatase is markedly elevated at 420 U/L. Triglycerides are normal. She denies taking statins. Which of the following best explains the presence of Lp-X in her serum?
Answer choices
- AImpaired hepatic synthesis of apolipoprotein B-100
- BDeficiency of lipoprotein lipase leading to accumulation of chylomicron remnants
- COverproduction of HDL particles in response to liver inflammation
- DIncreased intestinal synthesis of apolipoprotein B-48
- EBiliary obstruction prevents normal hepatic excretion of cholesterol and formation of bile acidsCorrect answer
- FMutations in ABCB4 gene impairing phospholipid export into bile
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.