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Vitamin B12 level

• Overview
• Risks
• Results

What the risks are:

Risks from having blood drawn are slight:

• Excess bleeding
• Fainting or feeling light-headed
• Blood under the skin (hematoma)
• Infection
• Many needle sticks to find veins

Special considerations:

The health care provider will usually take blood or red blood-cell folate levels when testing for megaloblastic anemias of any kind.

The blood test for levels of vitamin B12 has become much more accurate within the past few years. Now, there are fewer false-normal results, because the test only measures biologically active B12.

A Schilling test can find the cause of a vitamin B12 deficiency.

Rupture of some of the red blood cells (hemolysis) in the blood sample may affect test results.

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Getting a blood sample from some people may be harder than from others.

References:

Goldman L, Ausiello D. Cecil Textbook of Medicine . 22nd ed. Philadelphia, Pa: Saunders, 2003.

Hoffman R, Benz E, Shattil S, Furie B, Cohen H. Hematology: Basic Principles and Practice . 4th ed. Philadelphia, Pa: Churchill Livingstone, 2004.

• Review Date: 3/13/2007
• Reviewed By: Mark Levin, M.D., Hematologist and Oncologist, Newark, NJ. Review provided by VeriMed Healthcare Network.

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