From the Guidelines
Elevated vitamin B12 levels can be caused by various factors, including excessive supplementation, certain medical conditions, and medications, as well as underlying conditions such as liver disease, kidney disease, and certain blood disorders, as noted in a study published in the Journal of Clinical Oncology 1. When considering the potential causes of elevated vitamin B12 levels, it's essential to take into account the patient's medical history, current medications, and supplement use. Some medical conditions that can increase B12 levels include:
- Liver disease, such as cirrhosis or hepatitis
- Kidney disease
- Certain blood disorders, like polycythemia vera and chronic myelogenous leukemia
- Some solid organ cancers Medications that may elevate B12 levels include:
- Metformin, which can cause falsely high readings
- Oral contraceptives
- Proton pump inhibitors with long-term use Additionally, genetic factors can play a role, as some individuals have mutations affecting B12 transport proteins, as discussed in a study published in Genetics in Medicine 1. While high B12 levels are generally not harmful themselves, they often signal an underlying condition that requires medical attention. If you have unexpectedly high B12 levels, it's crucial to consult with a healthcare provider to determine the cause, especially if you're not taking supplements containing B12.
From the Research
Possible Causes of Elevated Vitamin B12 Levels
- Over-supplementation of vitamin B12, as high blood concentrations are often caused by excessive intake 2
- Macro-vitamin B12, an underrated cause of supra-physiological cobalamin plasma levels, which can lead to falsely elevated vitamin B12 values 2
- Certain disease entities, such as lung carcinoma, although the relationship between the disease and elevated vitamin B12 levels may not always be correlated 2, 3
- Cancer, as elevated vitamin B12 levels have been associated with a higher risk of cancer, with risk ratios ranging from 1.88 to 5.9 4
Clinical Implications and Diagnostic Considerations
- Elevated vitamin B12 levels can be a daunting diagnostic problem, and internists should be careful not to forget macro-vitamin B12 as a possible source of falsely elevated vitamin B12 values 2
- PEG precipitation can distinguish between a 'real' high vitamin B12 and macro-vitamin B12, and should be considered in cases of suspicion 2
- A high vitamin B12 concentration is no guarantee for adequate cobalamin storage, and further testing may be necessary to determine the underlying cause of elevated levels 2, 5