LDL stands for low-density lipoprotein. It's also sometimes called "bad" 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 to measure the level of LDL cholesterol in your blood. Too much LDL in the blood can clog arteries.
Low-density lipoprotein test
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.
In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.
You will usually be told not to eat or drink anything for 9 - 12 hours before the test.
The health care provider may tell you to stop taking certain drugs before the procedure.
When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may be some throbbing.
LDL carries cholesterol to various tissues throughout the body. Too much LDL, commonly called "bad cholesterol," is linked to cardiovascular disease. The lower your LDL, the lower your risk for heart disease or stroke.
A healthy LDL level is one that falls in the optimal or near-optimal range.
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
High levels of LDL may be associated with:
Lower than normal levels of LDL may be caused by:
Additional conditions under which the test may be performed:
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults. 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. Updated 2004.
U.S. Preventive Services Task Force. Screening for lipid disorders in adults: U.S. Preventive Services Task Force recommendation statement. Rockville (MD): Agency for Healthcare Research and Quality (AHRQ); 2008 Jun.
Semenkovich CF. Disorders of lipid metabolism. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 217.
Review Date: 5/23/2010
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