Lipid Biochemistry USMLE Step 1 Practice Question
A 7-year-old girl presents with orange-colored tonsils, lipemia retinalis, and recurrent pancreatitis. Vital signs: HR 98/min, BP 105/68 mmHg, RR 20/min, temp 37.2°C. Fasting labs reveal triglycerides 1,200 mg/dL and amylase 450 U/L; LDL cholesterol is normal. She denies abdominal pain currently. Genetic sequencing confirms homozygous loss-of-function mutation in the lipoprotein lipase gene. Which metabolic consequence best explains her severe hypertriglyceridemia?
Answer choices
- AImpaired hydrolysis of triglycerides in both chylomicrons and VLDL, resulting in accumulation of both particle typesCorrect answer
- BInability to hydrolyze triglycerides in VLDL particles; normal chylomicron clearance
- CSelective retention of chylomicrons in the intestinal lacteal system
- DExcessive apoC-II-mediated activation of hepatic triglyceride lipase
- EDecreased apoB-100 synthesis leading to reduced VLDL secretion
- FApoC-II deficiency causing failure to activate lipoprotein lipase
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.