Vitamin B12 testing

‘Why vitamin B12 is important for one’s health’ – Jan 8, 2012, Economic Times
‘Vitamin B12 eludes 8 out of 10 Indians’ – Sep 7, 2012, Times of India
‘Vitamin B12 deficiency can be sneaky, harmful’ – Harvard Health Blog, January 10, 2013
‘Tired? It could be vitamin deficiency’ – Hindustan Times , October 20, 2013


Why the sudden focus on Vitamin B12 testing?

The human body needs vitamin B12 to make red blood cells, nerves, DNA, and carry out other functions. Like most vitamins, B12 can’t be made by the body. It has to be obtained from food or supplements.

Some people don’t consume enough vitamin B12 to meet their needs, and others cannot absorb enough, so vitamin B12 deficiency is relatively common.

How necessary is it in today’s times?

“It is particularly important that the diagnosis of cobalamin deficiency be established with a high degree of certainty because cobalamin therapy almost always must be given for the life-time of the patient.” Stabler and Allen, 2004

How do I know if I am at risk?

There are many causes for vitamin B12 deficiency. Two of them are practices often undertaken to improve health: a vegetarian diet and weight-loss surgery.

Plants don’t make vitamin B12. The only foods that deliver it are meat, eggs, poultry, dairy products, and other foods from animals. Strict vegetarians and vegans are at high risk for developing a B12 deficiency if they don’t eat grains that have been fortified with the vitamin or take a vitamin supplement. People who have stomach stapling or other form of weight-loss surgery are also more likely to be low in vitamin B12 because the operation interferes with the body’s ability to extract vitamin B12 from food.

Conditions that interfere with food absorption, such celiac or Crohn’s disease, can cause B12 trouble. So can the use of commonly prescribed heartburn drugs, which reduce acid production in the stomach (acid is needed to absorb vitamin B12). The condition is more likely to occur in older people due to the cutback in stomach acid production that often occurs with aging. Elderly patients often fail to understand that a true vitamin B12 deficiency due to malabsorption requires life-long treatment.

The CBC and the serum cobalamin (B12) test should be included in the initial laboratory assessment of vitamin B12 deficiency.

What are normal results for this test?

Laboratory test results may vary depending on your age, gender, health history, the method used for the test, and many other factors. If your results are different from the results suggested below, this may not mean that you have a disease.

The following are considered to be normal results for this test:
Adults: >250 pg/mL (>185 pmol/L)

What do I do if my levels are below normal?

A common therapy is 1 milligram (1,000 µg) of vitamin B12 consumed daily. But it is recommended to consult your physician to determine the cause of your vitamin deficiency and discuss what is the most optimal dosage in your case.

How often do I need to be tested?

You may repeat your test 3 months after therapy or as per your doctor’s advice.


Stabler SP & Allen RH: Vitamin B12 deficiency as a worldwide problem. Annu Rev Nutr 2004; 24:299-326.