Biological or Clinical Significance:
HDL cholesterol (HDL-C) is a powerful inverse predictor of risk of coronary heart disease (CHD). Guidelines published by the American Heart Association (AHA) and the National Cholesterol Education Program (NCEP), which is sponsored by the National Heart, Lung and Blood Institute (NHLBI), recommend that physicians determine HDL-C levels together with other tests in a standard lipid profile prior to administering dietary or drug therapies for CHD. The NCEP guidelines state that patients with high cholesterol or borderline high cholesterol with risk factors (e.g. HDL-C less than 40 mg/dL, hypertension, smoking, family history, etc.) be tested for HDL-C. Subsequently, HDL-C and other lipid parameters should be measured 3-4 times per year to monitor the progress of therapy. Because of its protective effect, the NCEP has designated high HDL-C at or above 60 mg/dL as a negative risk factor.
Principle of Test Method:
In the HDL precipitation procedure described here, apo B-containing lipoproteins are removed by treating an aliquot of the serum with a dextran sulfate magnesium chloride reagent. The apo B-containing lipoproteins precipitate and are separated by centrifugation. The resulting HDL supernate is then measured for cholesterol, by an enzymatic procedure.