Beta-carotene is found in certain foods. It breaks down to become vitamin A in the body. A test can be done to measures the amount of beta-carotene in blood.
See also: Vitamin A test
A blood sample is needed. For information on how this is done, see: Venipuncture
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 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.
The examples above are common measurements for results of these tests. 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.
Increased levels may be due to taking too much vitamin A. See: Hypervitaminosis ALower-than-normal levels may occur when:
While this test is a valuable part of the diagnosis of vitamin A deficiency, 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:
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. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 87.