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)