Lowering Cholesterol

by Food and Drug Administration (FDA)

In the last 12 years, average cholesterol levels in the United States have dropped significantly, according to a recent report from the National Cholesterol Education Program (NCEP). We are now closer than ever to the Department of Health and Human Services' Year 2000 goal: a reduction in mean cholesterol level among adult Americans to 200 milligrams (mg) per deciliter (dL) of blood.

Yet, despite the good news of an overall drop in the average total cholesterol level — from 213 mg/dL to 205 mg/dL — an estimated 35 percent of Americans still need to lower their cholesterol to achieve a desirable level. Approximately 29 percent — or 52 million adults — could lower their cholesterol effectively with dietary therapy, according to the report. About 7 percent, or 12.7 million, would require additional drug therapy to lower cholesterol.

The new report recommends that the type of cholesterol- lowering therapy prescribed be based primarily on a person's risk of coronary heart disease (CHD). People at greatest risk — those who already have CHD or other atherosclerotic disease such as carotid (neck) artery disease — should receive the most aggressive treatment. This would most likely include a combination of drug and dietary therapy, and lifestyle changes such as increasing exercise and quitting smoking. Those at low risk would be counseled to begin making dietary changes and to eliminate other CHD risks from their lifestyle.

Defining Cholesterol

Cholesterol, part of the chemical group called lipids, is a component of all body cells, and plays an important role in hormone production and other vital body processes. Most cholesterol in the blood is produced by the liver; some is absorbed directly from cholesterol-rich foods, such as eggs and whole milk dairy products.

Cholesterol is carried in blood in the form of substances called lipoproteins. CHD risk can be assessed by measuring total blood cholesterol, as well as the proportions of the different types of lipoproteins. "Total" cholesterol refers to the overall level of cholesterol in the blood. High-density lipoprotein (HDL) is often referred to as "good" cholesterol, because high levels of HDL are associated with lowered CHD risk. High levels of low-density lipoprotein (LDL) — often referred to as "bad" cholesterol — and very low density lipoprotein (VLDL) increase CHD risk.

Fats called triglycerides are also carried in the blood in the form of lipoproteins. The role of triglycerides in the development of CHD is unclear. However, doctors may be concerned when patients have tests showing very high levels of triglycerides (more than 400 mg/dL) because fasting triglyceride tests are an indirect measure of VLDL. Therefore, they usually will want to investigate further.

Cholesterol Testing

The NCEP report recommends that all adults 20 years of age and older have their total cholesterol and HDL measured at least once every five years.

For people without CHD, a total blood cholesterol level of less than 200 mg/dL is considered "desirable"; from 200 to 239 mg/dL is "borderline-high"; and 240 mg/dL or more is "high." An HDL level of less than 35 mg/dL is defined as "low" and is considered a CHD risk factor.

A lipoprotein analysis, which measures LDL as well as HDL, is recommended for people with CHD or for those at very high risk of developing CHD. The goal of cholesterol-lowering therapy for high- risk individuals is an LDL cholesterol of about 130 mg/dL; for those with established CHD, the optimum LDL cholesterol is 100 mg/dL or lower.

Cholesterol testing requires a small sample of blood taken with a fingerstick. It can be done in a physician's office or at a commercial laboratory. Because cholesterol levels vary from day to day by as much as 20 to 40 mg/dL, at least two samples should be taken a week or more apart.

FDA cleared for marketing in March 1993 a device that can be used by consumers at home for initial screening of total cholesterol. (It is not to be used to monitor results of cholesterol-lowering therapy.) To use this device, the person places a drop of blood in a blood well. In approximately 10 to 15 minutes, a purple color advances up the measuring device, and the user reads it like a thermometer, explains FDA's Cornelia Rooks, branch chief of clinical chemistry in the Center for Devices and Radiological Health. The test result is obtained by comparing the height of the peak to a chart, which tells whether cholesterol is in a desirable, borderline, or high range. The device is used once and then discarded.

Natural variations in cholesterol may make home test results difficult to interpret, notes Margo Denke, M.D., assistant professor, department of internal medicine, University of Texas Southwestern Medical Center at Dallas, and member of the NCEP expert panel. "If someone does the home test several times and sees a variation, the person may [incorrectly] assume he or she is doing something 'right' when levels are lower and 'wrong' if the level rises," she says.

These devices may not yet be available at local pharmacies. At press time, a quick survey of chain pharmacies in the Washington, D.C., area found that most do not stock the product, though some will order it for customers. One reason given for not stocking the device was that it gives insufficient information so that consumers would be better advised to consult doctors for advice about cholesterol.

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.