HDL-C

HDL-C, or high-density lipoprotein cholesterol, is the concentration of cholesterol carried within high-density lipoprotein particles in the blood. It is typically reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L) and is one of the standard measurements included in a blood lipid panel .^1,2

HDL particles are a diverse group of lipoproteins that transport cholesterol and other lipids through the circulation. Among their functions, they can accept cholesterol from peripheral cells and participate in pathways that transport cholesterol toward the liver. HDL-C measures the amount of cholesterol contained within the circulating HDL particle population at the time of measurement .²

HDL-C is therefore not the same as HDL itself. HDL refers to the lipoprotein particles, which vary in size, composition, protein content, and biological activity. HDL-C measures only their cholesterol content. It does not directly measure the number of HDL particles, their capacity to accept cholesterol from cells, or other aspects of HDL function .²

Higher HDL-C concentrations have historically been associated with lower cardiovascular risk in observational studies, which led to HDL-C sometimes being described as “good cholesterol.” However, this association does not mean that HDL-C itself directly protects against cardiovascular disease, and pharmacologically increasing HDL-C has not consistently reduced cardiovascular events. HDL-C is therefore best understood as a measurable lipid biomarker rather than a direct measure of cardiovascular protection .²