A vitamin B12 level test checks the amount of vitamin B12 in the body. Normal levels usually range from 200 to 900 picograms per milliliter, but the way of measuring will depend on the laboratory. Vitamin B12 status is typically assessed by measurements of serum or plasma vitamin B12 levels. The cutoff between normal vitamin B12 levels and deficiency varies by method and laboratory, but most laboratories define subnormal serum or plasma values as those lower than 200 or 250 picograms per milliliter (pg/mL) (148 or 185 picomols per liter [pmol/L]) [2]. Levels of serum methylmalonic acid (MMA), a vitamin B12-associated metabolite, are the most sensitive markers of vitamin B12 status ... Optimal levels: The optimal vitamin B12 levels are generally considered to be between 400 and 600 pg/mL. It is important to note that vitamin B12 levels can fluctuate depending on various factors, including diet, health conditions, and the use of supplements. A vitamin B12 test can tell how much B12 you have in your body. Serious symptoms can come with having too much or too little and may be a sign of another condition.
