Lipid Biochemistry USMLE Step 1 Practice Question
A 41-year-old man with Type 2 diabetes presents with fatigue. Vital signs: BP 138/88 mmHg, HR 92 bpm, RR 16/min, Temp 37.0°C, SpO2 98% on room air. He denies chest pain. Labs show HDL cholesterol 28 mg/dL, triglycerides 280 mg/dL, LDL 145 mg/dL, and elevated fasting glucose of 156 mg/dL. He takes metformin and atorvastatin without improvement in lipid profile. A fibrate is added. Which mechanism best explains how fibrates improve his lipid abnormalities?
Answer choices
- AInhibition of intestinal cholesterol absorption
- BCompetitive inhibition of hepatic HMG-CoA reductase
- CDirect activation of hepatic cholesterol 7-alpha-hydroxylase
- DActivation of PPAR-alpha increases lipoprotein lipase expression and reduces triglyceridesCorrect answer
- EInhibition of hepatic apolipoprotein B-100 synthesis
- FInhibition of hepatic fatty acid synthase (FASN) reducing de novo lipogenesis
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