Vitamin B-12 is an essential vitamin with diverse roles in the body. It is important for blood cell synthesis, controls blood levels of the amino acid homocysteine, and aids in nervous system function. Vitamin B-12 also regulates the immune system and mood through control of S-adenosylmethionine. While vitamin B-12 deficiency is common among some populations, high levels of the vitamin are rare. This may be due to an underlying health condition.
Amounts
Your vitamin B-12 levels can be tested by a routine blood test. Normal blood plasma levels fall between 200 and 900 picograms per milliliter. Values of less than 200 picograms per milliliter are a sign of a vitamin B-12 deficiency. Elevated levels are rare. Results above 900 picograms per milliliter may indicate a condition that blocks the removal of excess vitamin B-12 from the blood to the urine.
Causes
Elevated levels of vitamin B-12 may be caused by an underlying health condition. Liver diseases including cirrhosis or hepatitis may cause high blood levels of vitamin B-12. In addition, myeloproliferative disorders such aspolycythemia vera and chronic myelocytic leukemia may produce high levels. If your test results are elevated beyond the normal range, your doctor may order a repeat test to check the reliability.
Dietary Sources
Vitamin B-12 is a water soluble molecule, and excess amounts usually leave the body through the urine. According to the Office of Dietary Supplements at the National Institutes of Health, there have been no observations of adverse effects in healthy individuals due to consuming large amounts of vitamin B-12 from food sources or supplements. Even large amounts of vitamin B-12-rich foods, such as milk, meat and eggs, should not affect blood plasma levels.
Interactions
Tell your doctor if you are taking any type of medication. Many drugs interact with vitamin B-12 and these may reduce the accuracy of your test results. Seizure medications, chemotherapeutics, colchicine, cholesterol-lowering drugs, H2 blockers and other medications for ulcers, as well as diabetes medications, all interact with vitamin B-12 in the body.
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