High cholesterol? Check your risk.

Should you be on a cholesterol-lowering drug? For millions of Americans who thought their cholesterol level was just fine, the answer to that question changed when the National Heart, Lung, and Blood Institute recently issued new guidelines for treating high cholesterol. The criteria nearly triple the number of adults who should be taking cholesterol-cutting drugs, from 13 million to 36 million, or nearly one-fifth of all adults in the U.S. Our sister publication, Consumer Reports on Health, calls the measures appropriate.

WHO'S AT RISK NOW?

Cholesterol, a waxy substance primarily made in the liver, travels through the bloodstream as a component of larger particles, known as lipoproteins. Low-density lipoprotein (LDL), the "bad" kind, dumps some of its cholesterol into the artery walls. High-density lipoprotein (HDL), the "good" kind, sweeps cholesterol out of the arteries. If your LDL level becomes too high or your HDL level too low, mainly because of a diet high in saturated fat, a lack of exercise, and genetic factors, cholesterol can build up in the blood and help form artery-clogging plaque.

The guidelines break risk down into several categories, depending on your chances of having a heart attack or dying of coronary disease. People at the highest risk need to reduce their LDL to the lowest level, under 100 milligrams per deciliter ...