From the Guidelines
A good workup for elevated vitamin B12 levels should include a comprehensive laboratory evaluation, starting with a CBC with differential, comprehensive metabolic panel with uric acid, lactate dehydrogenase, and liver function tests, as well as serum tryptase levels and vitamin B12 levels, as recommended by the NCCN clinical practice guidelines in oncology 1. The evaluation should focus on identifying underlying conditions that cause high B12, including myeloproliferative disorders, liver disease, kidney disease, and certain cancers.
- Key laboratory tests to consider include:
- Complete blood count with differential to assess for eosinophilia, dysplasia, monocytosis, or circulating blasts
- Comprehensive metabolic panel to evaluate liver and kidney function
- Serum tryptase levels to assess for myeloproliferative variants of hypereosinophilic syndrome
- Vitamin B12 levels to confirm the elevation and monitor for changes
- Additional testing may be considered based on the patient's history, symptoms, and physical examination findings, such as serology testing for parasitic infections, testing for antineutrophil cytoplasmic antibodies and antinuclear antibodies, and quantitative serum immunoglobulin levels 1.
- In some cases, bone marrow aspirate and biopsy with immunohistochemistry may be necessary to evaluate for underlying hematologic disorders, particularly if there is a high suspicion of myeloproliferative neoplasms with eosinophilia and TK fusion genes 1.
- A detailed medication and supplement history is essential to rule out excessive supplementation as the cause of elevated vitamin B12 levels.
- Consultation with a hematologist is recommended for significantly elevated levels or when initial workup suggests a hematologic disorder.
From the Research
Elevated Vitamin B12 Levels: Causes and Workup
Elevated vitamin B12 levels, also known as hypervitaminosis B12 or hypercobalaminemia, can be caused by various factors, including:
- Solid neoplasia (primary or metastatic) 2, 3, 4
- Acute or chronic hematological diseases, such as chronic myelogeneous leukemia, promyelocytic leukemia, polycythemia vera, and hypereosinophilic syndrome 2, 3, 4
- Liver disorders, including acute hepatitis, cirrhosis, hepatocellular carcinoma, and metastatic liver disease 2, 3, 4
- Monoclonal gammapathy of undetermined significance 2
- Renal failure 2
- Excess vitamin B12 intake 2
- Inflammatory or autoimmune diseases 2
- Transient hematological disorders, such as neutrophilia and secondary eosinophilia 2
Diagnostic Approach
When elevated vitamin B12 levels are detected, a full diagnostic workup is necessary to assess the presence of underlying disease 4. This may include:
- Complete blood count (CBC) to evaluate for hematological abnormalities
- Liver function tests to assess for liver disease
- Imaging studies, such as ultrasound or CT scans, to evaluate for solid neoplasia or other abnormalities
- Bone marrow biopsy to evaluate for hematological malignancies
- Renal function tests to assess for renal failure
- Screening for inflammatory or autoimmune diseases
- Review of medication use and dietary supplements to assess for excess vitamin B12 intake
Clinical Implications
Elevated vitamin B12 levels can have significant clinical implications, including: