Lipid Biochemistry USMLE Step 1 Practice Question
A 45-year-old man with a history of recurrent acute pancreatitis presents with eruptive xanthomas on his extensor surfaces. Vital signs show BP 138/82 mmHg, HR 88/min, RR 16/min, temp 37.2°C, SpO2 98%. Laboratory studies reveal triglycerides 3,500 mg/dL, total cholesterol 680 mg/dL, and lipase 180 U/L. Abdominal imaging shows pancreatic inflammation without ductal obstruction. Genetic testing confirms lipoprotein lipase gene mutation. Which pathophysiologic mechanism best explains his presentation?
Answer choices
- ADecreased synthesis of apolipoprotein B-100 in hepatocytes
- BImpaired hydrolysis of triglycerides in circulating chylomicrons and VLDLCorrect answer
- CDefective apolipoprotein C-II preventing VLDL uptake
- DIncreased activity of hepatic lipase leading to excessive lipolysis
- EImpaired clearance of LDL particles via hepatic receptors
- FEnhanced synthesis of triglycerides in adipose tissue with reduced peripheral lipolysis
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