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.

Apolipoprotein CII (apoCII) is in found in chylomicrons (large lipoprotein particles absorbed from the gastrointestinal tract) and VLDL (large lipoproteins that are broken down to eventually form LDL). ApoCII activates the enzyme that breaks down chylomicron and VLDL molecules.

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.

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:

• 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)

Elevated blood lipid levels (hyperlipidemia):
ApoCII measurements can help to determine the specific type or cause of hyperlipidemia. Abnormal values may exist in familial lipoprotein lipase deficiency (a rare inherited disorder causing high blood lipoprotein levels because of the lack of the enzyme to break down lipoproteins).

Low levels:
Low apoCII levels exist in familial apoprotein CII deficiency (a rare inherited disorder in which lack of apoCII causes the inability to activate the enzyme that breaks down lipoproteins, resulting in hyperlipidemia).

Other disorders that may be associated with elevated apoCII levels include:

• Angina pectoris
• Heart attack

• 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