Total blood cholesterol. High density lipoprotein (HDL) cholesterol. Low density lipoprotein (LDL) cholesterol. The cholesterol ratio.
Knowing about cholesterol is important in gauging your risk for a heart attack, and taking steps to lower the risk. Heart attacks are the No. 1 cause of death in the United States. About 1.2 million people have a heart attack each year, and 550,000 deaths occur. High blood cholesterol also is a factor in many strokes, or “brain attacks.” Yet understanding the risk means juggling an often-confusing array of terms like HDL, LDL, and that “ratio.”
Here is a clip-and-save guide to the cholesterol maze, plus information on a related group of fatty materials that also may affect your heart attack risk.
Total cholesterol is the most common measure of blood cholesterol and the only number many people get from the doctor. Cholesterol is measured in milligrams per deciliter (mg/dL) of blood. A total cholesterol reading less than 200 mg/dL means a low risk of heart disease and is the desirable level that everyone should try to attain; 200-239 is borderline high cholesterol, and 240 and over is high cholesterol.
Cholesterol exists in different forms and amounts that have a big impact on heart attack risk.
HDL cholesterol is the “good” form of cholesterol. It helps carry cholesterol out of the body, including cholesterol deposited inside blood vessels, where it may block the flow of blood. Those blockages in the coronary arteries, which supply blood to the heart's muscular walls, are the main cause of heart attacks.
For HDL cholesterol, remember that “higher is healthier.” A reading of 35 or less is the high-risk level, with 60 and above the desirable level.
The American Heart Association says that actual total cholesterol and HDL readings are the best way to identify high-risk people. Some doctors, however, think that total cholesterol is less important than proportion, or ratio, of total cholesterol to HDL. That's the ratio.
To find the ratio, divide HDL cholesterol into total cholesterol. A person with total cholesterol of 240 and HDL of 70, for instance, would have a cholesterol ratio of 3.4:1, usually stated as 3.4-to-1.
Lower ratios are healthier ratios. A ratio of 5.0:1 is the desirable level, and 3.5:1 is the optimum level.
LDL cholesterol is the “bad” form of cholesterol. It helps deposit cholesterol into blood vessels. For LDL cholesterol, remember that “lower is healthier.” A reading of 130 and below is the desirable level, 130-159 is borderline high, and 160 or above is high.
In addition to cholesterol, blood tests usually measure trigylcerides, which make up most of the body's fat. Common fats in the diet, including vegetable oils, margarine, and butter, also are triglycerides.
Experts are not sure how much triglycerides contribute to heart attack risk, but they believe that lower levels are healthier. A reading less than 200 is normal; 200-400 is borderline high, 400-1,000 is high, and above 1,000, very high.
Numbers alone may not be enough to tell your real risk of a heart attack or stroke. Ask the doctor to interpret the numbers based on your current health and other risk factors for heart disease. Those include, age, blood pressure, use of cigarettes, and family history of heart disease.
Fairly small cholesterol abnormalities may double the heart attack and stroke risk in a person with high blood pressure who smokes and had a parent who died young from heart problems. Those same blips may mean nothing in another person with no risk factors.
Use the cholesterol numbers and the doctor's advice to develop a personal action plan. It may mean diet and lifestyle changes alone or combined with cholesterol-lowering drugs.
Michael Woods is the Blade's science editor. Email him at firstname.lastname@example.org.