Differential Diagnosis for Elevated B12
- Single Most Likely Diagnosis
- Vitamin B12 supplementation: The most common cause of elevated B12 levels is recent or ongoing supplementation with vitamin B12, which can be taken orally or via injection.
- Other Likely Diagnoses
- Myeloproliferative neoplasms: Conditions like polycythemia vera, essential thrombocytosis, and primary myelofibrosis can lead to increased B12 levels due to elevated transcobalamin I, a protein that binds to B12.
- Liver disease: Certain liver conditions, such as liver cirrhosis or acute hepatitis, can cause an increase in B12 levels due to the release of stored B12 from damaged liver cells.
- Renal failure: Impaired kidney function can lead to elevated B12 levels, possibly due to decreased clearance of B12 or increased production of transcobalamin I.
- Do Not Miss Diagnoses
- Leukemia: Although less common, certain types of leukemia, such as chronic myeloid leukemia (CML), can cause elevated B12 levels. Missing this diagnosis could have severe consequences.
- Lymphoma: Some lymphoma subtypes can also lead to increased B12 levels, making it essential to consider this possibility to avoid delayed diagnosis and treatment.
- Rare Diagnoses
- Transcobalamin II deficiency: A rare genetic disorder characterized by a deficiency of transcobalamin II, a protein necessary for B12 transport and utilization, leading to elevated B12 levels.
- Gastric cancer: In rare cases, gastric cancer can cause elevated B12 levels, possibly due to increased production of transcobalamin I or other mechanisms.