Lipid Biochemistry USMLE Step 1 Practice Question
A 67-year-old man with peripheral vascular disease presents with chest discomfort. Vital signs: BP 158/92 mmHg, HR 88 bpm, RR 16, SpO2 98% on room air. He takes high-dose simvastatin. Labs show LDL cholesterol 95 mg/dL, lipoprotein(a) 85 nmol/L (normal <50), and normal triglycerides at 120 mg/dL. Troponin is negative. Despite achieving LDL goals, which lipoprotein fraction best explains his persistent cardiovascular risk?
Answer choices
- ALipoprotein(a) has proatherogenic and prothrombotic properties independent of LDL-CCorrect answer
- BLipoprotein(a) increases hepatic cholesterol synthesis by feedback inhibition
- CLipoprotein(a) is primarily composed of free cholesterol that cannot be measured by standard lipid panels
- DHigh lipoprotein(a) directly reduces lipoprotein lipase activity
- EElevated lipoprotein(a) inhibits the anticoagulant effects of statins
- FLipoprotein(a) competitively inhibits LDL receptor binding, preventing normal clearance of LDL particles from circulation
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