High-density lipoprotein (HDL cholesterol, HDL-C) is one of the classes of lipoproteins that carry cholesterol in the blood. HDL-C consists primarily of protein with a small amount of cholesterol. It is considered to be beneficial because it removes excess cholesterol from tissues and carries it to the liver for disposal. Hence, HDL cholesterol is often termed "good" cholesterol. The test for HDL cholesterol measures the amount of HDL-C in blood. High levels of cholesterol have been shown to be associated with the development of hardening of the arteries (atherosclerosis) and heart disease. When cholesterol levels in the blood increase (not enough is removed by HDL), it may be deposited on the walls of blood vessels. These deposits, termed plaques, can build up; causing vessel walls to become more rigid, and may eventually narrow the openings of blood vessels, constricting the flow of blood. HIGHER levels of blood HDL-C can decrease the risk of developing plaques by removing excess cholesterol from the blood. See Cholesterol, Total, Serum