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Beta-carotene is the precursor to vitamin A. A test can be done to measures the amount of beta-carotene in blood.
See also: Vitamin A test
Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.
Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.
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, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.
Do not eat or drink anything for 6 hours before the test. Your health care provider may also tell you to temporarily stop taking drugs, such as retinol, that may interfere with test results.
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.
Your doctor may order this test if you have signs of a vitamin A deficiency. Beta-carotene breaks down to become vitamin A in the body.
The test can also be used as an indirect way to measure how your body absorbs fats. Beta-carotene is a fat-soluble nutrient. That means it is stored in the body's fatty tissue
Fischbach FT, ed. Manual of Laboratory & Diagnostic Tests. 7th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2004.
Lewis JH. Liver disease caused by anesthetics, toxins, and herbal preparations. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger & Fordtran’s Gastrointestinal and Liver Disease. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2006:chap 84.
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