Lipid Biochemistry USMLE Step 1 Practice Question
A 52-year-old woman with prior myocardial infarction at age 48 presents with chest pain. Vital signs: BP 142/88 mmHg, HR 92/min, RR 16/min, Temp 37°C, SpO2 98%. Laboratory studies show LDL cholesterol 180 mg/dL despite atorvastatin 80 mg daily; HDL 35 mg/dL. Genetic testing reveals LDLR gene mutation. Coronary angiography shows significant atherosclerosis without acute thrombosis. Which pathophysiologic consequence best explains her severe hypercholesterolemia?
Answer choices
- AImpaired hepatic uptake of LDL particles due to nonfunctional LDL receptorsCorrect answer
- BReduced activity of HMG-CoA reductase in the liver
- CDecreased clearance of HDL particles by the kidneys
- DEnhanced intestinal absorption of dietary cholesterol
- EIncreased hepatic synthesis of apolipoprotein B-100
- FDefective apolipoprotein E leading to impaired remnant particle uptake by hepatic receptors
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