Lipid Biochemistry USMLE Step 1 Practice Question
A 55-year-old man with type 2 diabetes and chronic kidney disease (GFR 35 mL/min/1.73m²) presents with nephrotic syndrome and bilateral lower extremity edema. Vital signs: BP 148/92 mmHg, HR 88/min, RR 16/min, temp 37.2°C. Serum albumin is 2.1 g/dL with urine protein 8.5 g/day. Laboratory studies show total cholesterol 420 mg/dL, triglycerides 650 mg/dL, and HDL 22 mg/dL. Chest examination reveals clear lung fields. Which of the following best explains his severe hyperlipidemia?
Answer choices
- AChronic kidney disease directly decreases hepatic cholesterol synthesis
- BPrimary apolipoprotein C-II loss through proteinuria
- CGlomerular filtration of lipoproteins leading to selective renal clearance
- DDiabetes-induced inhibition of lipoprotein lipase by hyperglycemia alone
- EIncreased hepatic VLDL synthesis combined with impaired triglyceride clearanceCorrect answer
- FSecondary hyperparathyroidism causing increased intestinal cholesterol absorption and reduced fecal bile acid excretion
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