From the Guidelines
Your vitamin B12 level of 1663 pg/mL is above the normal reference range of 230-1050 pg/mL, indicating an elevated B12 level, which is defined as an overdose according to the ESPEN micronutrient guideline 1. This elevation is not typically associated with toxicity, as toxicity is defined by the presence of clinical signs or symptoms compatible with toxicity, which are generally not present in cases of elevated B12 levels 1. Some key points to consider:
- Elevated B12 can sometimes be associated with certain liver diseases, some blood disorders, or excessive supplementation, as defined by the ESPEN guideline as an overdose 1.
- If you're currently taking B12 supplements or multivitamins containing B12, you might consider reducing or stopping them after discussing with your doctor, to prevent further elevation of B12 levels.
- Most people get sufficient B12 from animal products in their diet, including meat, fish, eggs, and dairy, and excess B12 is stored in the liver, which explains why levels can become elevated with supplementation 1.
- Despite the elevation, there's no need for immediate concern as high B12 itself doesn't typically cause symptoms or health problems, and is generally asymptomatic, as stated in the ESPEN guideline 1. It is essential to consult with your healthcare provider to investigate potential underlying causes of this elevation and to discuss the best course of action, as the ESPEN guideline recommends careful assessment of inflammation and integration of systematic monitoring in clinical practice 1.
From the FDA Drug Label
CLINICAL PHARMACOLOGY Vitamin B12 is essential to growth, cell reproduction, hematopoiesis, and nucleoprotein and myelin synthesis. The FDA drug label does not answer the question.
From the Research
Vitamin B12 Levels
- The given vitamin B12 level is 1663 pg, which is above the normal range of 230-1050 pg.
- Elevated serum levels of vitamin B12, also known as hypervitaminosis B12 or hypercobalaminemia, can be associated with various health issues 2, 3.
- According to the literature, high serum levels of vitamin B12 can be related to solid neoplasia, acute or chronic hematological diseases, liver disorders, monoclonal gammapathy of undetermined significance, renal failure, and other conditions 2, 3, 4.
Health Implications
- A study found that incidental detection of serum vitamin B12 levels >1000 pg/mL is associated with a higher risk of neoplasia, with hypercobalaminemia and smoking being independent predictors of neoplasia 4.
- Elevated vitamin B12 levels can also be related to liver disease, with one study finding that 23.6% of patients with hypercobalaminemia had structural liver disease 4.
- Vitamin B12 status is also important in patients with chronic kidney disease (CKD), as impairment in vitamin B12 metabolism is considered a nontraditional risk factor of poor outcomes associated with CKD 5.
Diagnosis and Testing
- Serum B12 is still the most commonly used and widely available test for assessing vitamin B12 status, but diagnostics by holotranscobalamin, serum methylmalonic acid, and plasma homocysteine measurements have grown in routine practice 6.
- The lack of a robust absorption test, coupled with compromised sensitivity and specificity of other tests, can hinder determination of the cause for depleted B12 status and lead to incorrect supplementation regimes 6.