High levels of vitamin B-12 can be indicators of liver disease or myeloproliferative disorders, states MedlinePlus. Examples of these conditions include hepatitis, cirrhosis, myelocytic leukemia and polycythemia vera.
Myeloproliferative disorders cause abnormal growth of red blood cells, white blood cells or platelets in the bone marrow, explains the University of Maryland Medical Center. Although symptoms of these disorders vary depending on the specific condition, myeloproliferative disorders can cause fatigue, trouble breathing and abnormal bleeding.
Liver disease refers to conditions that affect the liver. Infection, cancer and genetics can cause liver diseases such as hepatitis, liver cancer and hemochromatosis, explains Mayo Clinic. Symptoms of liver disease can include yellow skin and eyes, dark urine and itchy skin.
A study by the Department of Clinical Biochemistry of Aarhus University Hospital in Denmark found that high vitamin B-12 levels increase the risk of blood cancers and cancers related to smoking and alcohol consumption, as reported by Medical Daily.
High vitamin B-12 levels are uncommon, considering that vitamin B-12 usually leaves the body during urination, states MedlinePlus. When this does not happen, it can indicate that something is not functioning correctly in the body. Consuming large quantities of vitamin B-12 in food or as a dietary supplement does not cause increased vitamin B-12 levels in the blood, reports SFGate.