Diagnosis

Doctors 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, the numbers of white blood cells and platelets also might be decreased and 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.
Nov. 09, 2016
References
  1. Kaushansky K, et al. Folate, cobalamin, and megaloblastic anemias. In: Williams Hematology. 9th ed. New York, N.Y.: The McGraw-Hill Companies; 2016. http://accessmedicine.mhmedical.com/content.aspx?sectionid=101237678&bookid=1581&Resultclick=2#1121092138. Accessed Oct. 10, 2016.
  2. Schrier SL, et al. Etiology and clinical manifestations of vitamin B12 and folate deficiency. http://www.uptodate.com/home. Accessed Oct. 10, 2016.
  3. 2015-2020 Dietary Guidelines for Americans. U.S. Department of Health and Human Services and U.S. Department of Agriculture. https://health.gov/dietaryguidelines/2015/guidelines/.  Accessed Oct. 10, 2016.
  4. Goldman L, et al., eds. Approach to the anemias. In: Goldman-Cecil Medicine. 25th ed. Philadelphia, Pa.: Saunders Elsevier; 2016. http://www.clinicalkey.com. Accessed Sept. 18, 2016.
  5. Pazirandeh S, et al. Overview of water-soluble vitamins. http://www.uptodate.com/home. Accessed Oct. 10, 2016.
  6. Vitamin C: Fact sheet for health professionals. National Institutes of Health Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/.  Accessed Oct. 10, 2016.
  7. Schrier SL. Diagnosis and treatment of vitamin B12 and folate deficiency. http://www.uptodate.com/home. Accessed Oct. 10, 2016.
  8. Walker BR, et al. Environmental and nutritional factors in disease. In: Davidson's Principles and Practice of Medicine. 22nd ed. London, England: Churchill Livingston Elsevier; 2014. http://www.clinicalkey.com.
  9. Folate: Fact sheet for health professionals. National Institutes of Health Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Folate-HealthProfessional/.  Accessed Oct. 10, 2016.
  10. Alcohol and public health: Frequently asked questions. Centers for Disease Control and Prevention. http://www.cdc.gov/alcohol/faqs.htm. Accessed Oct. 10, 2016.
  11. Mesa RA (expert opinion). Mayo Clinic, Rochester, Minn. Oct. 17, 2016.