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Apolipoprotein CIIDefinition 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, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic. An elastic band is placed around the upper arm to apply pressure and cause the vein to swell 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 band 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. In infants or young children: 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. A bandage may be applied to the puncture site if there is any bleeding. How to prepare for the test Fasting for 4 - 6 hours may be recommended. How the test will feel When the needle is inserted to draw blood, you may feel moderate pain, or 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). Normal Values 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 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: What the risks are
Special considerations 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. Illustrations
Page Content: ApoCII; Apoprotein CII |
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