Medical conditions that cause high vitamin B12 levels include liver diseases, such as cirrhosis and hepatitis, and myeloproliferative disorders, reports MedlinePlus. These conditions are very serious and often life-threatening, notes PubMed Central. In rare cases, patients with diabetes and obesity may have high B12 levels, according to WebMD.
The liver processes vitamin B12, and any disease or cancer that affects the functioning of the liver causes an increase in B12 levels in the blood, explains Everyday Health. These medical conditions include cirrhosis, acute hepatitis, metastatic liver disease and hepatocellular carcinoma, reports PubMed Central. These liver diseases may cause the release of vitamin B12 during hepatic cytolysis or affect the liver's ability to clear vitamin B12.
High levels of vitamin B12 can also indicate myeloproliferative disorders such as myelocytic leukemia and polycythemia vera, according to MedlinePlus. They may also indicate chronic myelogeneous leukemia and hypereosinophilic disorder, notes PubMed Central. Individuals who are obese or eat too much meat and individuals who suffer from diabetes may also have high vitamin B12 levels, explains Healthline.
To determine whether the patient has high levels of vitamin B12, doctors test a sample of his blood, according to MedlinePlus. Normal levels range between 200 and 900 picograms per milliliter. However, the results may differ by lab.