Lipid Biochemistry USMLE Step 1 Practice Question
A 64-year-old man with prior myocardial infarction presents with hypertension (BP 152/88 mmHg), heart rate 82 bpm, and denies chest pain. He takes atorvastatin 80 mg daily with LDL-cholesterol of 110 mg/dL and triglycerides of 95 mg/dL. Laboratory analysis reveals elevated lipoprotein(a) of 120 nmol/L (reference <50 nmol/L). Which of the following best explains his persistent cardiovascular risk despite adequate LDL-cholesterol control?
Answer choices
- AStatins increase hepatic synthesis of lipoprotein(a) through SREBP-2 activation
- BLp(a) inhibits the activity of tissue plasminogen activator, impairing fibrinolysis
- CLp(a) directly inhibits the expression of apolipoprotein A-I in HDL particles
- DLp(a) competes with LDL for hepatic receptors, preventing cholesterol feedback regulation
- ELp(a) is oxidized and taken up by macrophages, promoting foam cell formation and atherosclerosis independent of LDLCorrect answer
- FLp(a) binds to PCSK9 and prevents its degradation, leading to increased LDL receptor internalization despite adequate statin therapy
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