Apolipoprotein B100 (apoB100) is a protein that plays a role in metabolism. It is a form of low density lipoprotein (LDL).

This article discusses the test used to measure the level of apoB100 in the blood.

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.

Your health care provider may tell you not to eat or drink anything for 4 - 6 hours before the test.

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.

Most often, this test is done to help determine the cause or specific type of hyperlipidemia.

The normal range is 40 - 125 mg/dL.

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

An abnormal result may mean you have high lipid levels (hyperlipidemia).

Other disorders that may be associated with high apoB100 levels include angina pectoris and heart attack.

See also: Familial combined hyperlipidemia

• 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

Apolipoprotein measurements may give a much more accurate picture of your health, including your risk for heart disease.