Lipoproteins are complexes of proteins and lipids which are classified according to density into high-density lipoproteins (HDL) and low-density lipoproteins (LDL).
HDL binds excess cholesterol to remove it from cells. A higher blood level of HDL-cholesterol (HDL-Chol) or “good” cholesterol is a protective mechanism against atherosclerotic changes. LDL-cholesterol or “bad” cholesterol promotes cholesterol deposition on the walls of blood vessels. A high blood level of LDL-cholesterol is a prognostic indicator for atherosclerosis.