Retinol test
The vitamin A test measures the level of vitamin A in the blood.
Follow your health care provider's instructions about not eating or drinking anything for up to 24 hours before the test.
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterwards, there may be some throbbing or slight bruising. This soon goes away.
This test is done to check if you have too much or too little vitamin A in your blood. (These conditions are uncommon in the United States.)
Normal values range from 20 to 60 micrograms per deciliter (mcg/dL) or 0.69 to 2.09 micromoles per liter (micromol/L).
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.
A lower than normal value means you do not have enough vitamin A in your blood. This may cause:
A higher than normal value means you have excess vitamin A in your blood (toxic levels). This may cause:
Vitamin A deficiency may occur if your body has trouble absorbing fats through the digestive tract. This may occur if you have:
There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
Markell M, Siddiqui HA. Vitamins and trace elements. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 27.
Ross AC. Vitamin A deficiencies and excess. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 61.
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