http://www.nlm.nih.gov/medlineplus/ency/article/003705.htm
http://www.nlm.nih.gov/medlineplus/ency/article/000589.htm
An increased vitamin B12 level is uncommon. Usually, excess vitamin B12 is removed in the urine.
Conditions that can increase B12 level include:
- Liver disease (such as cirrhosis or hepatitis)
- Myeloproliferative disorders (for example, polycythemia vera and chronic myelocytic leukemia