Your doctor can determine the level of vitamin B-12 in your blood with a blood test. Low levels of vitamin B-12 may indicate a B-12 deficiency. Because the body absorbs only a small percentage of vitamin B-12 from foods and supplements, high levels of B-12 occur rarely. Elevated B-12 levels may indicate potentially serious underlying health problems.
B-12 Levels
Vitamin B-12 levels between 200 and 900 picograms per milliliter typically indicate normal B-12 status. Values below 200 pg/mL may indicate B-12 deficiency in healthy adults, and values below 500 pg/mL may indicate deficiency in older adults, notes MedlinePlus Medical Encyclopedia. Values above 900 pg/mL indicate a high vitamin B-12 level and may point to an underlying health problem.
Causes of Elevated B-12
A variety of health conditions can increase B-12 levels, including liver cirrhosis, hepatitis and myeloproliferative disorders such as polycythemia vera and chronic myelocytic leukemia, according to MedlinePlus Medical Encyclopedia. Polycythemia vera causes an abnormal increase in red blood cells, and leukemia can cause an abnormal increase in white blood cells.
Tolerable Upper Intake Level
The Institute of Medicine establishes a tolerable upper intake level, or UL, for nutrients that can cause adverse health effects when consumed in high amounts. Because vitamin B-12 has a low potential for toxicity, the Institute of Medicine has not established a UL value for this nutrient, according to the National Institutes of Health Office of Dietary Supplements. Doctors may use oral doses of vitamin B-12 as high as 2,000 mcg to treat deficiencies.
Recommended B-12 Intake
Children ages 9 to 13 should get 1.8 mcg of vitamin B-12 per day, and adolescents and adults ages 14 and over should get 2.4 mcg per day, according to the National Institutes of Health Office of Dietary Supplements. Pregnant women need 2.6 mcg per day and lactating women need 2.8 mcg per day. Good sources of vitamin B-12 include animal products such as seafood, meat, poultry and dairy, as well as fortified cereals and dietary supplements.
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