Normal values are 200 - 900 pg/mL (picograms per milliliter).

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about what your specific test results mean.

Values of less than 200 pg/mL are a sign of a vitamin B12 deficiency. People with this deficiency are likely to have or develop symptoms. Older adults with vitamin B12 levels between 200 and 500 pg/mL may also have symptoms.

Causes of vitamin B12 deficiency include:

• Not enough vitamin B12 in diet (rare except with a strict vegetarian diet)
• Diseases that cause malabsorption (for example, celiac disease and Crohn's disease)
• Lack of intrinsic factor
• Above normal heat production (for example, with hyperthyroidism)
• Pregnancy

Increased vitamin B12 levels are uncommon. Usually excess vitamin B12 is removed in the urine.

Conditions that can increase B12 levels include:

• Liver disease (such as cirrhosis or hepatitis)
• Myeloproliferative disorders (for example, polycythemia vera and chronic myelocytic leukemia)

Review Date: 03/21/2010
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; James R. Mason, MD, Oncologist, Director, Blood and Marrow Transplantation Program and Stem Cell Processing Lab, Scripps Clinic, Torrey Pines, California.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)