The LDL test measures how much low-density lipoprotein (LDL) you have in your blood. LDL is a type of cholesterol . Too much LDL in the blood can clog arteries.

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.

You may 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.

This test is usually done to determine your risk for heart disease. The LDL test is usually done as part of a lipid analysis, which also checks for total cholesterol, HDL, and triglycerides.

LDL is carries cholesterol to various tissues throughout the body. Too much LDL, commonly called "bad cholesterol," can lead to cardiovascular disease.

According to the National Heart, Lung, and Blood Institute, 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.

• Optimal: Less than 100 mg/dL (less than 70mg/dL for persons with a history of heart disease or those at very high risk for atherosclerotic disease)
• Near Optimal: 100-129 mg/dL
• Borderline High: 130-159 mg/dL
• High: 160-189 mg/dL
• Very High: 190 mg/dL and higher

Normal value ranges may vary slightly among different laboratories.

High levels of LDL may be associated with:

• Increased risk of atherosclerotic heart disease
• Familial hyperlipoproteinemia

• Malabsorption (inadequate absorption of nutrients from the intestinal tract)
• Malnutrition

• Familial combined hyperlipidemia
• Familial dysbetalipoproteinemia
• Familial hypertriglyceridemia

• 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

Drugs that can increase lipoprotein levels include aspirin, oral contraceptives, phenothiazines, corticosteroids, and sulfonamides.

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.