Medical Encyclopedia: HDL (Print Version)
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Medical Encyclopedia: HDL
URL of this page: http://www.nlm.nih.gov/medlineplus/ency/article/003496.htm
Alternative names
High-density lipoprotein
Definition
HDL stands for high density lipoprotein, a form of "good" cholesterol. Lipoproteins are proteins in the blood that
move cholesterol, triglycerides, and other lipids to various tissues.
This article discusses the blood test used to measure levels of HDL cholesterol in your blood.
How the test is performed
A needle will be used to take a sample of blood from a vein, usually from the inside of the elbow or the back of the
hand.
First, the area will be cleaned with a germ-killing product (antiseptic). An elastic band is placed around your upper
arm to help the vein swell with blood, and the needle is inserted.
The needle is attached to an air-tight tube or syringe, which is used to collect the blood. During the procedure, the
band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the needle
stick area is covered with a small bandage to stop any bleeding.
How to prepare for the test
Do not eat anything for 9 - 12 hours before the test.
How the test will feel
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.
Why the test is performed
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, thus 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 the cholesterol part of HDL, not the actual amount of HDL in the
http://www.nlm.nih.gov/medlineplus/print/ency/article/003496.htm
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Medical Encyclopedia: HDL (Print Version)
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blood.
Normal Values
The normal value ranges may vary slightly among different laboratories.
In general, your risk for heart disease, including a heart attack, increases if your HDL cholesterol level is less than
40 mg/dL. More specifically, men are at particular risk if their HDL is below 37 mg/dL, and 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.
What abnormal results mean
Low HDL levels may indicate an increased risk of atherosclerotic heart disease.
Additional conditions under which the test may be performed:
z
z
Familial combined hyperlipidemia
Noninsulin-dependent diabetes (NIDD)
What the risks are
Risks associated with this test may include:
z
z
z
z
z
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
Special considerations
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.
References
Toth PP. Cardiology patient page. The "good cholesterol": high-density lipoprotein. Circulation. 2005 Feb 8;111
(5):e89-91.
Executive Summary of the Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on
Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). JAMA.
2001;285:2486-2497.
Update Date: 7/21/2006
Updated by: Benjamin W. Van Voorhees, MD, MPH, Assistant Professor of Medicine and Pediatrics, The University of Chicago, Chicago, IL.
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Medical Encyclopedia: HDL (Print Version)
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http://www.nlm.nih.gov/medlineplus/print/ency/article/003496.htm
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