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Answer · biomarkers

What is small dense LDL (sdLDL)?

Short answer

sdLDL measures cholesterol carried by small, dense LDL particles — the LDL subfraction most strongly tied to atherogenesis and metabolic syndrome.

Reviewed by Dr. Laura PurdyMay 29, 2026

Full answer

Small, dense LDL particles penetrate the arterial wall more easily and are more susceptible to oxidation than larger, buoyant LDL particles. Elevated sdLDL signals heightened cardiovascular risk independent of total LDL cholesterol and is common in insulin resistance and metabolic syndrome. Within oMeds review, sdLDL is reviewed in advanced cardiovascular workups alongside ApoB, LDL particle number, and triglycerides. Improving insulin sensitivity and reducing triglycerides typically reduces sdLDL burden.

Educational. Not a substitute for individualized provider review.

References & sources
  • Small Dense LDL — Primary source · oMeds
  • Reviewed by Dr. Laura Purdy, MD, MBA · Clinical Director, oMeds · Last reviewed 2026-05-29

Related answers

What is LDL-P?
LDL-P quantifies the absolute number of LDL particles by NMR spectroscopy. When LDL-P and LDL-C diverge, particle number better predicts cardiovascular risk.
Primary source
Small Dense LDL