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).  Alternative names:  ApoB100; Apoprotein B100.  The normal range is 40 to 125 mg/dl.
(mg/dl = milligrams per deciliter).  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: a) angina pectoris, and b) myocardial infarction

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 the risk for heart disease.

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).

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.

A test to measure the amount of apolipoprotein B100 (apoB100) in the blood.

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 restrict blood flow through the vein. This causes 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 you can provide for this or any test or procedure depends on your child’s
age, interests, previous experience, 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:

     infant test or procedure preparation (birth to 1 year)
     toddler test or procedure preparation (1 to 3 years)
     preschooler test or procedure preparation (3 to 6 years)
     schoolage test or procedure preparation (6 to 12 years)
     adolescent test or procedure preparation (12 to 18 years)

How it feels:  When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging
sensation. Afterward, there may be some throbbing.

Risks:  a) excessive bleeding; b) fainting or feeling lightheaded; c) hematoma (blood accumulating under the skin); d) infection (a slight risk anytime the skin is broken) multiple punctures to locate veins.

Why the test is performed:  Most often, this test is performed to help determine the cause of hyperlipidemia (elevated blood lipid levels).