HDL stands for high density lipoprotein, a form of "good" cholesterol. Lipoproteins are made of fat and protein. They carry cholesterol, triglycerides, and other fats, called lipids, in the blood to various parts of the body.

This article discusses the blood test used to measure levels of HDL cholesterol in your blood.

See also:

• LDL test ("bad" cholesterol)
• Lipid profile
• High blood cholesterol and triglycerides
• Total cholesterol test

A blood sample is needed.

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

Do not eat anything for 9 - 12 hours before the test.

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

This test is done to check the level of cholesterol in your blood and to see if you are at high risk fo a heart attack, stroke, or other cardiovascular problem. Studies of both men and women have shown that the higher your HDL, the lower your risk of coronary artery disease. This is why HDL is sometimes referred to as "good" cholesterol.

The main function of HDL is to help soak up excess cholesterol from the walls of blood vessels and carry it to the liver, where it breaks down and is removed from the body in the bile.

The laboratory test for HDL actually measures how much cholesterol is in the HDL, not the actual amount of HDL in the blood.

In general, your risk for heart disease, including a heart attack, increases if your HDL cholesterol level is less than 40 mg/dL.

Men are at particular risk if their HDL is below 37 mg/dL.

Women are at particular risk if their HDL if their HDL is below 47 mg/dL.

An HDL 60 mg/dL or above helps protect against heart disease.

Women tend to have higher HDL cholesterol than men.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

Low HDL levels may indicate an increased risk of atherosclerotic heart disease.

They also may be associated with:

• Familial combined hyperlipidemia
• Noninsulin-dependent diabetes (NIDD)

Risks associated with this test may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)
• Multiple punctures to locate veins

HDL will usually be done as part of an overall lipid profile, where "bad" cholesterol (LDL) and triglycerides will also be measured. The combined information gathered from all of these tests may help your risk of heart attack, stroke, and peripheral vascular disease.

Your health care provider will recommend therapy if your risk is found to be high. Regular exercise can increase HDL levels by several points.

Gaziano M, Manson JE, Ridker PM. Primary and secondary prevention of coronary heart disease. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 45.