A patient with abdominal pain and eruptive xanthomas has triglycerides of 4500 mg/dL. LPL assay shows absent activity. Which lipoprotein accumulates in type I hyperlipoproteinemia (familial LPL deficiency)?

• A IDL (intermediate-density lipoprotein)
• B LDL
• C Chylomicrons and VLDL ✓
• D HDL and LDL

Explanation

LPL (lipoprotein lipase) is anchored to capillary endothelium by heparan sulfate and hydrolyzes triglycerides in chylomicrons and VLDL, generating fatty acids for uptake by muscle, adipose, and heart. ApoC-II (on chylomicron/VLDL surface) is the essential LPL activator. In LPL deficiency, chylomicrons (postprandial) cannot be cleared and accumulate dramatically; VLDL also accumulates. The resulting severe hypertriglyceridemia (>1000 mg/dL) causes eruptive xanthomas, lipemia retinalis, and acute pancreatitis. LDL requires separate hepatic lipase activity and LDLR.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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