Accurate cholesterol reading requires ratio rather than total

November 01, 1994|By Medical Tribune News Service

Many women are needlessly alarmed and may be treated unnecessarily when told that their cholesterol level places them at increased risk of heart disease, according to Pennsylvania researchers.

Because women generally have higher levels of high-density lipoproteins (HDLs, the so-called "good" cholesterol), they can be misclassified as high risk when physicians rely on total cholesterol readings as a screening test, according to the study in today's issue of the Annals of Internal Medicine. Total cholesterol is a mixture of HDLs with two types of "bad cholesterol" -- low-density lip oproteins and very-low-density lipoproteins.

Researchers at the University of Pennsylvania re-analyzed blood test results on 8,000 men and women who participated in three long-term studies of heart disease. In those studies, the ratio of total cholesterol to HDLs was the best predictor of who would develop heart disease in the next eight to 10 years.

For example, in the large Framingham Heart Study, women with a total cholesterol/HDL ratio higher than 9 were three times more likely to suffer a heart attack or develop other signs of coronary heart disease than on average. Neither the level of total cholesterol nor the level of low-density lipoproteins was as helpful in predicting risk.

"People should ask for their ratio, or at least make sure that their RTC HDL level is taken into account when their risk is assessed. They are often looked at quite differently, but a person with a total cholesterol of 300 and an HDL of 59 is at exactly the same risk as someone with a total cholesterol of 200 and an HDL of 40," said co-author Dr. Bruce Kinosian, an assistant professor of medicine at the University of Pennsylvania Medical Center.

While applauding the effort to find better heart-disease predictors, the coordinator of the National Cholesterol Education Program challenged the assumption that HDL levels are currently being ignored.

"The current guidelines do not ignore HDL. They consider an HDL below 35 as a risk factor, and an HDL 60 or above as a negative risk factor -- something that is protective," said Dr. James I. Cleeman. "It's an overstatement from what they found to say too many women are treated unnecessarily."

Unlike measurement of low-density lipoproteins, a person need not fast before having their blood taken for total cholesterol/HDL ratio.

A total cholesterol/HDL ratio of five is about average, while a ratio of 4.5 or below is generally considered desirable, says Dr. Kinosian.

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