B12 Deficiency and Testing

Knowing the facts about vitamin B12 and its benefits is vital: this essential micronutrient affects the development and maintenance of red blood cells, nerve cells, and normal myelination (covering) of nerve cells. It also aids in the production of DNA, RNA, and neurotransmitters. And, your metabolism can’t run smoothly without enough of it.

In an article by Skerrett, published by the Harvard Medical School (2013), Vitamin B12 deficiency can be long term, insidious, and present with often mis- or un-diagnosed symptoms. Symptoms may include:

  • strange sensations, numbness, or tingling in the hands, legs, feet, or mouth
  • difficulty walking (staggering, balance problems)
  • anemia
  • a swollen, inflamed tongue
  • mouth ulcers
  • yellowed skin (jaundice)
  • difficulty thinking and reasoning (cognitive difficulties), or memory loss
  • paranoia or hallucinations
  • weakness
  • fatigue
  • depression
  • sleeping issues

Alone or individually, these symptoms may not mean that you have a B12 deficiency, but combined with other risk factors, this is certainly a possibility. Unfortunately, symptoms of a vitamin B12 deficiency can take years to show up, and diagnosing it can be complex. A B12 deficiency can sometimes be mistaken for a folate deficiency.

Folks that may be most at risk include:

  • take a proton-pump inhibitor (such as Nexium or Prevacid) or H2 blocker (such as Pepcid or Zantac)
  • take metformin (a diabetes drug)
  • are a strict vegetarian
  • have had weight-loss surgery or bowel surgery removing certain parts of the bowel.
  • have a condition that interferes with the absorption of food such as Crohn’s Disease or Celiac Disease
  • 50 years of age or older
  • high stress lifestyle

If you suspect you have B12 deficiency, the first step is to get tested. You need an accurate baseline to work from. There are various ways to be tested for B12. Routine blood work generally gives a point in time of the B12 levels. This means for that exact moment of the blood draw, your blood plasma levels of B12 were at “X” level. However, this value isn’t actually all that significant, since the test also measures the vitamin B12 which the body cannot use. Unfortunately, a clinical deficiency within the cells can be present even when vitamin B12 levels show up as normal in the blood.

While this is not a bad way to test, there are advanced laboratories that utilize the white blood cells (lymphocytes) to look at more of a trend or average of B12 levels over a 3-6 month period. This type of specialty testing provides more long-term information about your overall B12 status instead of what you last ate and absorbed to change your plasma levels in the last 24-hours (SpectraCell Laboratories, 2018).

Finally, it is possible to test for B12 levels by a urine test. By measuring the concentration of various metabolic products which change with the occurrence of a cellular vitamin B12 deficiency; namely the concentrations of homocysteine and methylmalonic acid (MMA), it is possible to determine a B12 deficiency in the face of normal B12 labs. “During a vitamin B12 deficiency, the concentration of methylmalonic acid rises both in the blood and in the urine. There is only one vitamin B12 dependent metabolic pathway for conversion of MMA. Thus, MMA urine test is a reliable indicator as to whether a functional vitamin B12 deficiency is present or not. A distortion in results is only clinically possible with certain rare hereditary diseases, serious nutritional deficiencies and a rare bacterial overgrowth in the intestinal tract” (Rotter, n.d.).

If you are B12 deficient, the next step is to identify the mechanism causing the deficiency. This is something you’ll probably need help with from your medical practitioner. Once the mechanism is identified, the appropriate form (injection, oral, sublingual or nasal) of supplementation, the dose and the length of treatment can be selected.

At SNVHS, we have the ability to look into your nutritional status for B12 supplementation suggestions and treatment using normal labs, advanced lab testing, and use of urine samples. All labs are done at outside laboratories. If you are interested in what your overall B12 levels are OR would like to discuss B12 supplementation, give us a call!


Skerrett, P.J. (2013, Jan. 10). Vitamin B12 deficiency can be sneaky, harmful. https://www.health.harvard.edu/blog/vitamin-b12-deficiency-can-be-sneaky-harmful-201301105780

SpectraCell Laboratories. (2018). Nutritional Status and Health. https://www.spectracell.com/clinicians/products/mnt/

Rotter, D. (n.d.). Vitamin B12 Deficiency Urine Test. http://www.b12-vitamin.com/urine-test/