Blood test
Blood test

HDL

Definition

The HDL cholesterol is a test that measures the amount of high-density lipoprotein (HDL)cholesterol in serum.

Alternative Names

High-density lipoprotein

Why the Test is Performed

This test is used in an evaluation of coronary risk factors.

Lipoproteins are proteins in the blood that transport cholesterol, triglycerides, and other lipids to various tissues. The main function of HDL appears to be carrying excess cholesterol (and probably other phospholipids and proteins) to the liver for "re-packaging" or excretion in the bile.

Higher levels of HDL seem to be protective against coronary artery disease, thus HDL is sometimes referred to as "good" cholesterol. The laboratory test for HDL actually measures the cholesterol part of HDL, not the actual concentration of HDL in the blood.

This is also true of the tests for low density lipoprotein (LDL) and very low density lipoprotein (VLDL). The total cholesterol level is the sum of LDL, HDL, and VLDL cholesterol.

How the Test is Performed

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic. An elastic band is placed around the upper arm to apply pressure and cause the vein to swell with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. A bandage may be applied to the puncture site if there is any bleeding.

How to Prepare for the Test

Fast for 8 to 12 hours before the test.

Infants and children:
The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust. For general information regarding how you can prepare your child, see the following topics:

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.

Risks

Risks associated with this test may include:

Considerations

HDL will usually be performed as part of an overall lipid profile, wherein LDL and triglycerides will also be measured. The combined information gathered from all of these tests may help determine cardiovascular event risk (risk of heart attack, stroke, and peripheral vascular disease). Appropriate therapy will be prescribed if risk is shown to be high.

Normal Results

Women tend to have higher HDL cholesterol than men. In general, an increased risk for heart disease, including heart attack, occurs when the HDL level is less than 40mg/dL. More specifically, men are at particular risk if their HDL is below 37 mg/dL, and women, if their HDL is below 47 mg/dL.

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

Normal value ranges may vary slightly among different laboratories.

What Abnormal Results Mean

Low HDL levels may indicate an increased risk ofatherosclerotic heart disease.

Additional conditions under which the test may be performed:
Review Date: 8/6/2004
Reviewed By: Jonathan Harding, MD, CPE, Department of Medicine, University of Massachusetts Medical School, Worcester, MA. Review provided by VeriMed Healthcare Network.
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