Description
Use: A protective substance utilized for prediction of coronary arterial disease, especially useful in individuals with high serum cholesterol levels. Low HDLC is an important predictor of risk of coronary atherosclerosis and coronary heart disease. HDL may act as a protective scavenger molecule (reverse cholesterol transport). The liver is the major site of cholesterol excretion.
Reference Interval: <40 mg/dL is the cutpoint for increased CHD risk; high HDL cholesterol levels (=60 mg/dL) decrease CHD risk.
Additional Information: Total cholesterol and triglycerides are required as well for determination of lipid risk factors for coronary artery disease. These tests with HDLC and LDLC are the usual lipid panel. HDLC is especially apt to be low in male subjects who are obese and sedentary, in those who smoke cigarettes, and in those who have diabetes mellitus. Uremia is also associated with lower HDLC. Exercise, appropriate diet and moderate ethanol intake increase HDLC.
HDLC is useful with cholesterol in forecasting protection against coronary artery disease in the industrialized countries, possible because of ingestion of high fat diets. LDLC, an excellent predictor, is usually a calculation. Those at least risk for development of coronary arterial disease would have low cholesterol, low triglyceride, and high HDLC.
Thiazides and nonselective ß-adrenergic blocking agents may decrease HDLC.
Apolipoprotein A-1 determination may eventually be shown to be superior to HDLC; increased apoprotein A-1 is associated with a diminished risk of atherogenesis. It is measured by RIA3 and by nephelometry. Apolipoprotein A-1 is the major protein of HDL. Essentially, current studies have not yet answered whether or not apoprotein A-1 is a better discriminator than HDL.4 At present, HDL measurement is considered preferable by Gordon and Rifkind.
Factors contributing to decreased HDLC include:
• genetic factors: primary hypoalphalipoproteinemia
• cigarette smoking
• obesity
• hypertriglyceridemia
• lack of exercise
• steroids - androgens, progestogens, anabolic
• thiazides
• beta-adrenergic blockers
• probucol
• neomycin