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Answer · biomarkers

What is ApoA1?

Short answer

ApoA1 is the principal protein component of HDL particles and a central player in reverse cholesterol transport.

Reviewed by Dr. Laura PurdyMay 29, 2026

Full answer

ApoA1 anchors HDL particles and supports their cholesterol-clearing function. Low ApoA1 is associated with metabolic syndrome and increased cardiovascular risk. While HDL cholesterol mass is widely reported, ApoA1 protein concentration is more standardized and is increasingly used alongside ApoB to compute the ApoB/ApoA1 ratio — one of the strongest single-number cardiovascular risk discriminators in large outcome studies. Within oMeds review, ApoA1 is interpreted alongside ApoB, triglycerides, and metabolic context.

Educational. Not a substitute for individualized provider review.

References & sources
  • ApoA1 — Primary source · oMeds
  • Reviewed by Dr. Laura Purdy, MD, MBA · Clinical Director, oMeds · Last reviewed 2026-05-29

Related answers

ApoB/ApoA1 ratio?
The ApoB/ApoA1 ratio compares atherogenic particle burden to HDL protein, summarizing lipid-driven cardiovascular risk in a single number.
Primary source
ApoA1