Vitamin A blood testRetinol test
The vitamin A test measures the level of vitamin A in the blood.
How the Test is Performed
How to Prepare for the Test
Follow your health care provider's instructions about not eating or drinking anything for up to 24 hours before the test.
How the Test will Feel
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.
Why the Test is Performed
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 15 to 60 micrograms per deciliter (mcg/dL) or 0.52 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 doctor about the meaning of your specific test results.
What Abnormal Results Mean
A lower than normal value means you do not have enough vitamin A in your blood. This may cause:
- Bone or teeth problems in young children
- Dry or inflamed eyes
- Night blindness
- Recurring infections
- Skin rashes
- Reduced growth
- Dry skin
A higher than normal value means you have excess vitamin A in your blood (toxic levels). This may cause:
- Hair loss
- Loss of appetite
- Bone and muscle pain
- Increased pressure in the brain (pseudotumor cerebri)
- Double vision
- Liver and spleen enlargement
- Lack of muscle coordination (ataxia)
Vitamin A deficiency may occur if your body has trouble absorbing fats through the digestive tract. This may occur if you have:
- Chronic lung disease called cystic fibrosis
- Pancreas problems, such as swelling and inflammation (pancreatitis) or the organ not producing enough enzymes (pancreatic insufficiency)
- Small intestine disorder called celiac disease
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:
- Excessive bleeding
- Multiple punctures to locate veins
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Chernecky CC, Berger BJ. Vitamin A (retinol) - serum. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:1175-1177.
Ross AC, Tan L. Vitamin A deficiencies and excess. In: Kliegman RM, Stanton BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 48.
Salwen MJ. Vitamins and trace elements. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 26.
Review Date: 11/20/2017
Reviewed By: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.