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Tests and diagnosis
By Mayo Clinic staffDoctors diagnose vitamin deficiency anemias through blood tests that check:
- The number and appearance of red blood cells. People with anemia have fewer red blood cells than normal. In vitamin deficiency anemias related to a lack of vitamin B-12 and folate, the red blood cells appear large and underdeveloped. In advanced deficiencies, white blood cells and platelets also look abnormal under a microscope.
- The amount of folate, vitamin B-12 and vitamin C in your blood. Folate and vitamin B-12 levels are measured at the same time, because these deficiencies can cause similar signs and symptoms.
Additional tests for B-12 deficiency
If blood tests reveal a vitamin deficiency, your doctor may perform other tests to determine the type and cause, such as:
- Antibodies test. Your doctor may draw a sample of your blood to check for antibodies to intrinsic factor. Their presence indicates pernicious anemia.
- Methylmalonic acid test. You may undergo a blood test to measure the presence of a substance called methylmalonic acid. The level of this substance is higher in people with vitamin B-12 deficiency.
- Schilling test. In this test, you first ingest a tiny amount of radioactive vitamin B-12. Then your blood is checked to see if your body absorbed the vitamin B-12. After that, you ingest a combination of radioactive vitamin B-12 and intrinsic factor. If the radioactive B-12 is absorbed only when taken with intrinsic factor, it confirms that you lack your own intrinsic factor.
References
- Antony AC. Megaloblastic anemias. In: Hoffman R, et al. Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa.: Churchill Livingstone Elsevier; 2009. http://www.mdconsult.com/books/about.do?about=true&eid=4-u1.0-B978-0-443-06715-0..X5001-8--TOP&isbn=978-0-443-06715-0&uniqId=230100505-56. Accessed Jan. 24, 2011.
- Pernicious anemia. National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/dci/Diseases/prnanmia/prnanmia_all.html. Accessed Jan. 24, 2011.
- Zile M, et al. Vitamin C (ascorbic acid). In: Kliegman RM. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa.: Saunders Elsevier; 2007. http://www.mdconsult.com/das/book/body/208746819-6/0/1608/0.html. Accessed Jan. 27, 2011.
- Mason JB. Vitamins, trace minerals and other micronutrients. In: Goldman L, et al. Cecil Medicine. 23rd ed. Philadelphia, Pa.: Saunders Elsevier; 2008. http://www.mdconsult.com/das/book/body/191371208-2/0/1492/0.html#. Accessed Jan. 27, 2011.
- Dietary reference intakes (DRIs): Recommended intakes for individuals, vitamins. Institute of Medicine. http://iom.edu/en/Global/News%20Announcements/~/media/Files/Activity%20Files/Nutrition/DRIs/DRISummaryListing2.ashx. Accessed Jan. 28, 2011.
- USDA National Nutrient Database for Standard Reference, Release 23. U.S. Department of Agriculture. http://www.nal.usda.gov/fnic/foodcomp/search. Accessed Jan. 28, 2011.
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