Apolipoprotein A1

The Apolipoprotein A1 test quantifies Apo A1 to help assess risk for atherosclerotic cardiovascular disease and its complications. This measurement complements standard lipid studies for a more complete appraisal of HDL-related function. In conjunction with apolipoprotein B, results are used to calculate the apoB/apoA1 ratio, an alternative risk marker that may refine stratification beyond the traditional lipid panel. The assay also supports follow-up during lipid-lowering therapy and other interventions. Common synonyms include Alpha Apolipoprotein and Apo A1.

Apolipoproteins are the protein constituents of lipoprotein particles that enable the solubilization and intravascular transport of cholesterol and triglycerides. High-density lipoproteins, often referred to as "good" cholesterol, participate in reverse cholesterol transport by moving cholesterol from peripheral tissues to the liver for excretion or metabolic conversion, a process that helps protect the arterial wall from atherosclerotic changes. Within the Apo A family, apolipoprotein A1 is the predominant form, while apolipoprotein A2 is present in lower abundance. Apo A1 activates pathways that load cholesterol into HDL particles and thereby supports HDL-mediated efflux. Lower Apo A1 concentrations are associated with a greater likelihood of atherogenesis and an increased risk of adverse cardiovascular events.