Vitamin B-12 level

Normal values:

• 200 to 900 pg/ml

Note: pg/ml = picogram per milliliter

What abnormal results mean:

Values of less than 100 pg/ml (picogram per milliliter) indicate a clinically significant deficiency of vitamin B12 (symptoms are likely to be present or develop).

Causes of deficiency B12 include:

• inadequate intake (rare except with strict vegetarian diet)
• malabsorption diseases (for example, celiac disease and sprue)
• lack of intrinsic factor
• hypermetabolic state (for example, with hyperthyroidism)
• pregnancy

Increased vitamin B12 levels are uncommon, because normally excessive B12 is excreted in the urine. However, it may occur with disorders that affect the levels of proteins that bind vitamin B12 in the serum, including:

• hepatic (liver) disease (such as cirrhosis or hepatitis)
• myeloproliferative disorders (for example, myelocytic leukemia)

Additional conditions under which the test may be performed:

• anemia of B12 deficiency
• delirium
• dementia
• dementia due to metabolic causes
• megaloblastic anemia
• pernicious anemia