Testing for Vitamin B12 Deficiency
According to the National Institutes of Health, a person is considered to have a medical vitamin B12 deficiency with blood level values below 200 pg/ml. Levels between 200-350 pg/ml associated with elevated levels of MMA and homocysteine should also be considered low.[i]
Physicians typically conduct a simple blood test to measure vitamin B12 levels in the blood. Additionally, measuring for elevated methylmalonic acid (MMA) and homocysteine levels may be an even more sensitive way to screen for B12 deficiency than measurement of serum B12 levels alone.[ii]
- Elevated levels of the metabolites MMA and homocysteine have been recognized as a precursor to B12 deficiency.v
- Up to 50 percent of patients with subclinical B12 deficiency have normal B12 levels but elevated MMA and homocysteine levels.v
- However, it’s important to note that elevated MMA and homocysteine can be caused by other conditions, such as renal insufficiency.[iii]
[i] National Institutes of Health. Dietary Supplement Fact Sheet: Vitamin B12. Accessed November 2014. https://myds.nih.gov/en/content/vitamin-b12-32#.VGPke_nF98E.
[ii] Emisphere Technologies Inc. Eligen B12 white paper sales aid. Roseland, NJ. Accessed 2014