Vitamin B12 is one of eight B vitamins that your body needs to maintain the health of your nerve and blood cells, as well as assist in the making of DNA, MayoClinic.com reports. Also known as cobalamin, this vitamin is, like the other seven B vitamins, water-soluble. But as is not the case with the other B vitamins, many years' worth of thiis nutrient is stored in your liver, making vitamin B12 deficiencies rare. When a deficiency in vitamin B12 does occur, it is usually because your body is unable to use the vitamin. This inability is most often caused by a disease called pernicious anemia.
Vitamin B12 Level Test
To determine how much vitamin B12 there is in you blood, you need to take a vitamin B12 level test, MedlinePlus reports. This test requires you to fast from six to eight hours before the test and for you to inform the one giving you the test of all the medications you are taking, including over-the-counter medications and herbal preparations. Drugs such as colchicine, neomycin, para-aminosalicylic acid and phenytoin can affect the results of the test. A normal range for this test is from 200 to 900 picograms per milliliter (pg/mL). If your test value is less than 200 pg/mL, you are probably suffering from vitamin B12 deficiency. The same is true if you are an older adult and your test result is between 200 and 500 pg/mL.
Schilling Test
You can take a Schilling test to determine whether or not your body is absorbing vitamin B12 normally, MedlinePlus reports. This test has four stages, the first of which has you take a small dose of a radioactive form of vitamin B12 orally. An hour later, you will be give a larger injection of the vitamin. Over the next 24 hours, you will collect your urine and have it analyzed. If stage one is abnormal, stage two will be performed and this involves taking radioactive B12 along with a protein called intrinsic factor. If the results of stage two are abnormal, it's onto stage three, which involves taking antibiotics for two weeks and a dose of B12. If the results of this stage are abnormal, stage four, which involves taking pancreatic enzymes for three days, followed by a radioactive dose of vitamin B12, will be performed. A normal result is one in which you urinate from 8 to 40 percent of the radioactive vitamin B12 within 24 hours.
Availability
Vitamin B12 is plentiful in the typical diet in the United States. You can get the vitamin from fish, shellfish, meat and dairy products. The vitamin is bound to the protein in food. A meal consisting of a chicken breast, a hard-boiled egg and a cup of plain, low-fat yogurt or a cup of milk and a cup of raisin bran is enough to supply you with your daily requirement of vitamin B12, MayoClinic.com reports.
Dosing
If you are male, 14 years old or older, you need 2.4 mcg every day. In a pregnant female, that requirement increases to 2.6 mcg/day, MayoClinic,com reports, and if nursing, 2.8 mcg/day. About 10 to 30 percent of older people are not able to absorb vitamin B12 from their food effectively and because of this need to meet their daily requirements for this vitamin by eating foods fortified with vitamin B12, or by a taking a supplement that contains this vitamin. For children who are from 9 to 13 years old, 1.8 mcg/day is considered adequate intake. Children 4 to 8 years old need about 1.2 mcg/day, while children aged from 1 to 3 years 0.9 mcg/day. Infants from 7 to 12 months old need 0.5 mcg/day while those 6 months old and younger need even less, 0.4 mcg/day.
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