The normal range for vitamin B12 levels is from about 110 to 1,500 picograms per milliliter (pg/mL), according to WebMD. Vitamin B12 levels are determined from a standard blood test.
High levels of vitamin B12 may occur in those suffering from liver disease or certain forms of leukemia. Low levels of vitamin B12 may indicate vitamin B12 deficiency anemia, tapeworm, hyperthyroidism or folic acid deficiency anemia. Those recovering from gastric bypass surgery or small intestine removal may suffer from a loss of vitamin B12; other conditions that interfere with intestinal absorption of vitamins can also cause a deficiency, according to MedlinePlus. Pregnancy and older people are more likely to suffer from vitamin B12 deficiency.