High levels of vitamin B12 might be caused by several conditions including leukemia, liver disease, obesity and diabetes, according to WebMD. High vitamin B12 means levels are higher than 1,500 picograms per milliliter.
It is possible, based on certain conditions, that a vitamin B12 test may be inconclusive or incorrect, claims WebMD. Taking certain medications, for instance, may affect the test results. Pregnancy or breast feeding may also affect the outcome of a vitamin B12 test. Taking large amounts of vitamin C or drinking alcohol before the test can also affect the outcome. People who have had a computed tomography scan in the week before a vitamin B12 blood test, or those who have pernicious anemia may also have skewed results. It is also important for a person to fast for at least 12 hours before the test in order to get accurate results.
In most cases, a vitamin B12 test is done at the same time as a folic acid test, explains WebMD. This is done because lack of either may lead to anemia. Vitamin B12 may be stored in the liver for a year or more, which also helps to lower the risk of anemia. Eating enough of the foods that are rich in vitamin B12 is also important as it helps to regulate vitamin B12 levels. These foods include milk, eggs, cheese and shellfish.