High-Density Lipoprotein (HDL)

High-density lipoproteins (HDL) are plasma proteins that function as carriers of plasma cholesterol . Measuring the cholesterol contained in the HDL molecule is predictive of the individual's risk for coronary artery disease . 

It is believed that the HDL molecule carries cholesterol from the peripheral tissues of the body to the liver, where the cholesterol is converted into bile acids and eventually excreted. Cholesterol that is part of the high-density lipoprotein molecule will not be deposited in blood vessel walls. Because of this, HDL is sometimes referred to as the "good" cholesterol and is believed to have a protective effect on the circulatory system.

Normal Range

 

Men
>45 mg/dl
Women
>55 mg/dl

Variations from Normal. Some variations in high-density lipoprotein levels are based on gender and age. Increases in HDL levels are not often seen as problematic. However, since the liver is responsible for the metabolism of HDL, a nontherapeutic elevation of HDL levels can signify liver disease.
Most individuals are more concerned about low HDL levels.
Decreased availability of high-density lipoproteins may leave more cholesterol free to be deposited in the peripheral tissue of the body. Low levels of HDLs increase the risk of ASHD.

Interfering Circumstances. Lifestyle factors that influence HDL levels include smoking and alcohol ingestion, which decreases HDLs. Exercise can raise HDL levels. Drugs that may cause a lipoprotein increase are aspirin, oral contraceptives, steroids, and sulfonamides.