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Apolipoprotein B100 |
| Definition: |
| A test to measure the amount of apolipoprotein B100 (apoB100) in the blood. Lipoproteins are large complexes of molecules that transport lipids (primarily triglycerides and cholesterols) through the blood. Apolipoproteins are proteins on the surface of the lipoprotein complex that bind to specific enzymes or transport proteins on the cell membranes; this directs the lipoprotein to the proper site of metabolism. ApoB100 is in IDL (an intermediate form of lipoprotein) and LDL (low density lipoprotein). |
| Alternative Names: |
| ApoB100; Apoprotein B100 |
| How the test is performed: |
| Adult or child: Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and cause veins below the tourniquet to distend (fill 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 tourniquet 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. Infant or young child: 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. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding. |
| How to prepare for the test: |
| Fasting for 4 to 6 hours may be recommended. Infants and children: The physical and psychological preparation a parent can provide for this or any test or procedure depends on the child's age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
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| How the test will feel: |
| When the needle is inserted to draw blood, some people may feel moderate pain, while others may feel only a prick or stinging sensation. Afterward, there may be some throbbing. |
| Why the test is performed: |
| Most often, this test is performed to help determine the cause of hyperlipidemia (elevated blood lipid levels). ApoB100 is a form of apo-B that occurs in LDL and IDL but not in chylomicrons (large lipoprotein particles that contain apoB48 and other apolipoproteins). |
| Normal Values: |
| The normal range is 40 to 125 mg/dl. Note: mg/dl = milligrams per deciliter |
| What abnormal results mean: |
| Elevated levels of apo-B occur in familial combined hyperlipidemia and acquired hyperlipidemia (elevated blood lipid levels; ApoB100 measurements can help to determine the specific type or cause of hyperlipidemia). Other disorders that may be associated with elevated apo-B levels include: |
| What the risks are: |
| Special considerations: |
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Unlike HDL and LDL measurements (which are indirect), apolipoprotein levels can be measured directly. This test may give a much more accurate picture of your health, including your risk for heart disease. |
Reviewed By: Steven Angelo, M.D. Department of Internal Medicine, Yale School of Medicine, Hospital of Saint Raphael, New Haven, CT. Review provided by VeriMed Healthcare Network.
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