Vitamin B12

A vitamin B12 test measures the amount of Reference vitamin B12 Opens New Window in the blood.

The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what’s normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

High values

• High levels of vitamin B12 can occur in liver disease (such as Reference cirrhosis Opens New Window or Reference hepatitis Opens New Window) and some types of Reference leukemia Opens New Window. But the vitamin B12 test is not usually used to diagnose these problems.
• In rare cases, high levels may be found in people with Reference diabetes Opens New Window or who are Reference obese Opens New Window.

Low values

• Low levels of vitamin B12 may mean you have Reference vitamin B12 deficiency anemia Opens New Window, which might be caused by problems with the absorption of the vitamin (such as Reference pernicious anemia Opens New Window).
• Low levels may also occur following removal of part or all of the stomach (gastrectomy), gastric bypass surgery, or gastric stapling surgery, or following surgery to remove part of the small intestine where this vitamin is absorbed (terminal ileum).
• Low levels may mean an infection with a Reference parasite Opens New Window called fish tapeworm is present.
• In rare cases, low levels may mean a person is not getting enough vitamin B12 in his or her food.
• Low levels are linked with Reference hyperthyroidism Opens New Window or Reference folic acid deficiency anemia Opens New Window.
• High levels of protein in the blood, such as from Reference multiple myeloma Opens New Window, can falsely decrease blood vitamin B12 levels.

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This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Reference Terms of Use. Reference How this information was developed to help you make better health decisions.