Lipid Biochemistry USMLE Step 1 Practice Question
A 68-year-old man with longstanding type 2 diabetes (BP 148/92, HR 88, on atorvastatin 80 mg daily) presents with advanced atherosclerosis. Current labs show LDL cholesterol 95 mg/dL (goal-achieved) and apolipoprotein B 135 mg/dL (elevated). Fasting triglycerides are 320 mg/dL. He denies chest pain. Which mechanism best explains his persistently elevated apoB despite apparently controlled LDL cholesterol concentrations?
Answer choices
- AIncreased number of small, cholesteryl ester-depleted LDL particles each carrying one apoB moleculeCorrect answer
- BOverproduction of large, triglyceride-enriched VLDL particles
- CImpaired hepatic clearance of apoB-48-containing chylomicrons
- DEnhanced production of HDL particles containing apoB
- EDecreased catabolism of LDL receptors on hepatocytes
- FReduced conversion of intermediate-density lipoprotein (IDL) to large LDL particles due to hepatic lipase deficiency
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