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Ask Dr. K: Heart disease risk is not based on cholesterol alone

DEAR DOCTOR K: I am 71 years old. My LDL cholesterol is 160, but my HDL is 122. Does my high HDL cancel out concerns about my high LDL cholesterol?

DEAR READER: I can’t give you a definite answer for a simple reason: There are very few people like you. Therefore, there are few studies of people like you. Here’s what we know.

For the vast majority of people, the higher your LDL (“bad”) cholesterol, the greater your risk of heart disease. In contrast, the higher your HDL (“good”) cholesterol, the lower your risk.

What does this mean for you? Your HDL cholesterol is very high. I’ve had only one patient with an HDL level that high. Most people have an HDL level of 40-55. We call an HDL level “high” when it is over 60. Yours is 122. That’s very high.

Your high LDL cholesterol puts you at higher risk. But does your high HDL cholesterol cancel out that risk? There is a formula that could be used to answer that question. That is the ratio of total cholesterol to HDL cholesterol. (“Total cholesterol” is the sum of LDL and HDL cholesterol in your blood.)

Your total:HDL ratio is 282:122, or 2.31. Based on data from the Framingham Heart Study, that means you are at less than half the average risk for a heart attack. So that would seem to be good news.

However, the Framingham Heart Study included very few people with an HDL cholesterol level as high as yours. So does the formula really apply to you? I just don’t know.

By way of background, LDL is a substance in your blood that carries cholesterol to plaques of atherosclerosis. As a result, the plaques swell with more cholesterol. That’s why we call LDL cholesterol “bad.”

HDL is a substance that removes cholesterol from plaques of atherosclerosis. Presumably, that’s why people with high levels of HDL have lower rates of heart attacks and strokes.

Until recently, your doctor would have looked at your cholesterol numbers to decide whether to prescribe cholesterol-lowering statin drugs. But the most recent cholesterol guidelines, issued last year by the American College of Cardiology and the American Heart Association, take a new approach. The new guidelines focus on overall heart disease risks, rather than cholesterol numbers alone, to guide treatment.

So what would I do if I were you? I agree with the most recent cholesterol guidelines. If you are at relatively high risk for heart trouble in the next decade, I would talk to your doctor about taking a statin drug. The guidelines define “relatively high risk” as greater than a 7.5 percent chance of getting heart disease. This is based on all of your risk factors — including smoking, blood pressure, blood sugar, high LDL cholesterol and family members with heart disease at a relatively young age.

Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.

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