ApoCII; Apolipoprotein CII
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.
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:
- 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)
- School age test or procedure preparation (6 to 12 years)
- Adolescent test or procedure preparation (12 to 18 years)
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
This test is usually performed to help determine the cause of hyperlipidemia (elevated blood lipid levels).
Usually, apoCII is reported as “present” or “absent.” If the specific level is measured, the normal value may vary according to the institution performing the test.
What abnormal results mean
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 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
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
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 may be more difficult from some people than from others.
by Brenda A. Kuper, M.D.
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.