HDL checkup recommended.

Healthy people getting a blood test for total serum cholesterol should get their high-density lipoprotein (HDL) checked as well. That advice comes from an independent advisory panel appointed by the National Institutes of Health in Bethesda, Md.

HDL, often called the "good cholesterol," is a transport molecule that removes cholesterol and other potentially damaging fatty substances from the bloodstream. Scientists believe that abnormally low HDL levels increase the risk of coronary artery disease, which develops when heart arteries become clogged with fatty deposits (SN: 9/9/89, p.171). This can lead to a heart attack.

Total serum cholesterol values don't gof far enough in calculating a person's risk of heart disease, the panel asserted last week. The National Cholesterol Education Program considers total serum cholesterol levels of less than 200 milligrams per deciliter (mg/dl) within the desirable range. However, after reviewing a raft of studies on the subject, the panel concluded that people with desirable total serum cholesterol may nonetheless run a heightened risk of coronary artery disease if their serum HDL levels fall below 35 mg/dl.

The NIH panel also evaluated scientific data on triglycerides--fatty substances used by the body for energy storage. The panel declined to advocate routine screening for this fat because the evidence for a direct link between triglycerides and heart disease remains inconclusive. However, high triglyceride levels may increase levels of several clotting factors that boost heart attack risk, the panel warned.

Americans with total cholesterol levels within recommended limits but who have low HDL or high triglyceride values should reconsider the familiar advice to stop smoking, lose weight and exercise, says panel chairman Elliot Rapaport of the University of California, San Francisco. The panel notes that cigarette smoking decreases HDL levels and is a "powerful risk factor for coronary heart disease." Frequently, a weight-loss program combined with a fitness regimen can raise HDL and decrease triglyceride levels, thereby lowering the risk of heart disease, Rapaport says.