Vitamin B12 is an essential vitamin that is vital for red blood cell formation, according to the National Cancer Institute. Vitamin B12 is also useful for the maintenance of a healthy nervous system. Lack of vitamin B12 can cause a type of anemia called pernicious anemia as well as neurological problems. Normal levels of vitamin B12 in the blood are 200 to 900 pg/mL, according to MedlinePlus. Some patients may have higher levels of vitamin B12 due to several reasons.
Overdose
The recommended daily intake of vitamin B12 for adults is 2.4mcg. Patients who overdose on vitamin B12 on a single episode may experience high levels of the vitamin in their blood, according to Drugs.com. Other patients may experience high levels of vitamin B12 after abusing multivitamins and other supplements containing vitamin B12 for long periods of time. Patients taking prescribed vitamin B12 supplements should consult their doctor before taking over-the-counter multivitamins in order to avoid vitamin B12 overdose.
Liver and Kidney Failure
Vitamin B12 is metabolized in the liver and excreted by the kidneys, according to Drugs.com. Patients who have problems with the normal functioning of the liver and kidneys may not be able to excrete excess vitamin B12 and this leads to high levels of the vitamin in their bloodstream. Such patients should avoid taking high doses of multivitamins containing vitamin B12 without their doctor's consent.
Over Consumption of Foods High in Vitamin B12
Vitamin B12 is mainly found in animal products such as shellfish, eggs, red meat, pork, milk, dairy products and poultry. Patients who eat large amounts of such foods may have high levels of vitamin B12 in their bloodstream. However, people who do not eat animal products may be at risk for developing vitamin B12 deficiency because the only reliable source of the vitamin are animal products.
