Why it's done

High cholesterol usually causes no signs or symptoms. A complete cholesterol test is done to determine whether your cholesterol is high and to estimate your risk of heart attacks and other forms of heart disease and diseases of the blood vessels.

A complete cholesterol test includes the calculation of four types of fats in your blood:

• Total cholesterol. This is a sum of your blood's cholesterol content.
• Low-density lipoprotein (LDL) cholesterol. This is called the "bad" cholesterol. Too much of it in your blood causes the buildup of fatty deposits (plaques) in your arteries (atherosclerosis), which reduces blood flow. These plaques sometimes rupture and can lead to a heart attack or stroke.
• High-density lipoprotein (HDL) cholesterol. This is called the "good" cholesterol because it helps carry away LDL cholesterol, thus keeping arteries open and your blood flowing more freely.
• Triglycerides. Triglycerides are a type of fat in the blood. When you eat, your body converts calories it doesn't need into triglycerides, which are stored in fat cells. High triglyceride levels are associated with several factors, including being overweight, eating too many sweets or drinking too much alcohol, smoking, being sedentary, or having diabetes with elevated blood sugar levels.

Who should get a cholesterol test?

According to the National Heart, Lung and Blood Institute (NHLBI), a person's first cholesterol screening should occur between the ages of 9 and 11 and then be repeated every five years after that.

The NHLBI recommends that cholesterol screenings occur every 1 to 2 years for men ages 45 to 65 and for women ages 55 to 65. People over 65 should receive cholesterol tests annually.

More-frequent testing might be needed if your initial test results were abnormal or if you already have coronary artery disease, you're taking cholesterol-lowering medications or you're at higher risk of coronary artery disease because you:

• Have a family history of high cholesterol or heart attacks
• Are overweight
• Are physically inactive
• Have diabetes
• Eat an unhealthy diet
• Smoke cigarettes

People undergoing treatment for high cholesterol require regular cholesterol testing to monitor the effectiveness of their treatments.