Apoprotein B100

Alternative names
ApoB100; Apolipoprotein B100


This test measures 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 an intermediate form of lipoprotein (IDL) and an low density lipoprotein (LDL).

How the test is performed

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 airtight 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:

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 apoB 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.

What abnormal results mean

Elevated levels of apoB 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 apoB levels include angina pectoris and Heart attack .

What the risks are

  • 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

Special considerations

Apolipoprotein levels can be measured directly, unlike HDL and LDL measurements, which are indirect. This test may give a much more accurate picture of your health, including your risk for Heart disease.

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 others.

Johns Hopkins patient information

Last revised: December 5, 2012
by David A. Scott, M.D.

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.