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The beta-carotene test measures the level of beta-carotene in the blood.
A blood sample is needed.
Follow your health care provider's instructions about not eating or drinking anything for up to 8 hours before the test. You may also be asked not to eat anything with vitamin A (carotene) for 48 hours before the test.
Your provider may also tell you to temporarily stop taking medicines, such as retinol, which may interfere with test results.
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing and slight bruising. These soon go away.
Beta-carotene is found in certain foods. It breaks down to become vitamin A in the body.
Your health care provider may order this test if you have signs that your vitamin A level may be too low, such as:
The test can also be used to help measure how well your body absorbs fats.
The normal range is 50 to 300 micrograms per deciliter.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.
A higher than normal level may be due to taking too much vitamin A (hypervitaminosis A).
Beta-carotene deficiency may occur if you are malnourished. It can also occur if your body has trouble absorbing fats through the digestive tract such as with:
This test plays a valuable role in diagnosing vitamin A deficiency. But the test results must be evaluated along with other clinical findings.
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.
Other risks associated with having blood drawn are slight but may include:
Mason JB. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 225.
Salwen MJ. Vitamins and trace elements. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 26.