By Peter M. Abel, M.D.
Medical Director,
Prevention Center for Cardiovascular Disease
Cardiocascular Institute of the South

What your total cholesterol reading doesn't tell you could be hazardous to your health -- or a cause of undue alarm.

Until fairly recently, it was assumed that folks with blood cholesterol levels below 200 mg/dl (milligrams per deciliter) were at a lower-than-average risk for heart disease, while those at 200 and above were at increased risk. Like many assumptions, that one proved too simplistic.

There are two types of cholesterol -- a good kind, called high-density lipoprotein (HDL) -- and a bad kind, called low-density lipoprotein (LDL). What really turns out to be important, isn't the total of HDL and LDL, but the ratio between them.

For instance, a patient having a total cholesterol number of 161 -- quite good, on the old below-200 standard -- could be at a high risk if his good (HDL) cholesterol made up only 17 points of that total. The National Cholesterol Education Panel now classifies low HDL levels -- below 35 mg/dl -- as a major risk factor for heart disease. So our patient with a composite reading of 161 might be at the very opposite end of the risk scale than he thought.

On the other hand, someone with a cholesterol reading of 236 might actually benefit from that high reading -- if, for instance, her HDL level accounted for 74 points of it. An HDL reading above 60 is now recognized as actually lowering your risk of atherosclerosis -- "hardening of the arteries" -- which is the chief cause of heart attacks.

(Actually, even this is a slight oversimplification. There is a third kind of cholesterol, called LP(a), which is found in elevated levels in members of families with a strong history of heart disease. Ordinary cholesterol screenings don't even measure LP(a).)

At best, a cholesterol screening -- even one that differentiates between the two main types of lipoprotein -- is just a snapshot. A good HDL/LDL ratio isn't a permanent blessing, and a bad ratio isn't an irreversible pronouncement of doom. There are many ways to alter the ratio of good to bad cholesterol -- and one very good reason for improving it. A consistently high HDL level can not only slow the accumulation of LDL plaque, it can actually reduce what's already there.

&copy 1995 Cardiocascular Institute of the South