Vitamin B12, also known as Cobalamin, is one of the most important B vitamins and the last of the eight water-soluble vitamins that help in making red blood cells, serve as a co-factor on DNA synthesis, amino acid metabolism, synthesis of fatty acids and many more essential functions. It chiefly targets towards the healthy functioning and development of the brain as it plays an important role in the synthesis of myelin. Additionally, it also helps in boosting the immune system, fortifies bone health, prevents neural tube defects, promotes healthy skin and hair and actively treats different conditions like diabetes, diabetic neuropathy, nerve damage in the hands or feet, swollen tendons, male infertility, insomnia, AIDS, inflammatory bowel disease, diarrhea, asthma, allergies, age-related macular degeneration (AMD), cataracts, problems related to the mouth etc.

Also Read: Vitamin B12: Functions, Food Sources, Deficiencies and Toxicity

Vitamin B12 deficiency and Vitamin B12 test

What Is Vitamin B12 Deficiency And How Does It Affect?

Since Vitamin B12 is a quintessential nutrient required in the healthy functioning and growth of the body, a lack of it is can lead to different types of anomalies especially one being folate deficient anemia. In most cases, cobalamin deficiency causes different types of anaemia and other neurodegenerative diseases.  Being a B12 vitamin deficient may also make one prone to easy bruising or bleeding, cause blurred vision, fever, walking difficulties, gastrointestinal side effects including upset stomach, diarrhoea, irritable bowel syndrome, flatulence, constipation, Crohn’s disease, celiac disease, sore tongue, and weight loss. However, if the lack of this healthful nutrient is not corrected on time and left untreated, it can eventually lead to severe nerve and brain damage causing depression, disorientation and dementia and even temporary infertility in women.

Also Read: Vitamin B 12: Deficiency, Symptoms And Treatment

How Is It Diagnosed?

The Vitamin B12 deficiency is usually diagnosed by a blood or urine test preferably at the doctor’s chamber by a pathologist. This test chiefly checks the level of vitamin B-12 in the blood or urine to gauge the body’s overall vitamin B-12 stores. The test usually measures either of the following or sometimes even all of them.

  • Overall vitamin B-12
  • Methylmalonic acid (MMA)
  • Holotranscobalamin (holoTC)
  • Homocysteine

Several studies surface that MMA and holoTC can sometimes be more accurate at reading low B-12 levels since they represent active B-12.

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Types Of Vitamin B12 Deficiency Test

Blood Test: The blood test is a simple one where the pathologist generally draws blood from the vein after cleaning the area, tying a rubber or elastic band above it and using a needle to draw blood. Once the blood is drawn, the area is slightly pressed and band-aid is stuck to gradually stop bleeding. Although the vitamin B12 test alone doesn’t require following any specific food timing, in case your doctor is checking other components in the blood, he or she may ask you not to eat or drink for about six to eight hours before your test and ensure you are well hydrated.

Urine Test: The urine test can be done by collecting the urine sample in a jar and sending it to the laboratory. Sometimes, this urine test can even be done at home by purchasing test strips just like a pregnancy tester. This test strip needs to be dipped in the urine sample and the results are interpreted as suggested in the leaflet that comes with it. Most urine tests usually analyze the presence of MMA, i.e., Methylmalonic acid which is linked to early stages of a vitamin B-12 deficiency.

When Does A Doctor Suggest Vitamin B12 Deficiency Test?

The doctor might suggest you go for a vitamin B12 deficiency test if he or she notices any of the characteristic symptoms such as tingling sensations in the hands and feet, weakness, fatigue, nerve damage, light-headedness, confusion, rapid heartbeat, rapid breathing, loss of appetite and pale colour of the skin. Additionally, the doctor might ask you to conduct this test if he or she suspects that you are suffering from pernicious anemia which reduces the red blood cell count within your body and is usually diagnosed by diarrhea, constipation, loss of appetite, pale skin, exhaustion, inflamed tongue and bleeding gums.

A vitamin B12 test is also suggested if you are diagnosed with high serum folate levels. The primary function of folic acid is the growth of body and the production and development of red and white blood cells. But having high folate levels in the blood often mask the symptoms of vitamin B12 deficiency and in most situations worsens them altogether.

Who All Require A Vitamin B12 Test?

Like most water-soluble vitamins, our body doesn’t naturally produce vitamin B-12 and it mostly gets washed away from the body, hence one should consume a diet enriched in vitamin B12 food choices to prevent the deficiency syndromes. And this essential nutrient is usually sufficed by consuming animal products like fish, meat, and dairy. Hence, people who are vegetarians or vegans have a direct risk of suffering from vitamin B12 deficiency. Even older adults, children, people who are suffering from diabetes and those who had gastric bypass surgery have an aggravated chance of having cobalamin deficiency. Certain health conditions may also affect the body’s ability to absorb vitamin B12 from food. These include pernicious anemia, atrophic gastritis, celiac disease, or Crohn’s disease. Even certain medications like proton pump inhibitors, H2 receptor blockers or the ones used to treat diabetes may adversely affect the body’s vitamin B12 levels.

How To Interpret Vitamin B12 Results?

Once your blood or urine is analyzed, the doctor usually sends a detailed report regarding the levels of vitamin B12 found in the sample. Both high and low level suggests an underlying anomaly. While a sufficiently high level of B-12 may increase your risk for developing cancer in later stages or could be a sign of suffering from diabetes, liver disease, certain types of leukemia or early stages of kidney failure, a considerable low amount of vitamin B12 can also suggest anemia, infection from an internal parasite, neurological symptoms or even hyperthyroidism.

The vitamin B12 is usually measured on picograms per milliliter (pg/mL)   

It is considered low, if the range is below 150 pg/mL

A normal reading if it is 200 to 600 pg/mL        

A high level if the test result is 800 pg/mL         

For urine tests, a normal range for MMA is usually under 3.8 mcg/mC. A higher level usually indicates vitamin B12 deficiency. Similarly, the normal range for holoTC is 23–100 pmol/L. A low holoTC result is an early indicator of low B-12.

However, these numbers are just estimates, you can even be healthy and do not have any health condition even if your result is slightly higher or lower than the given normal range. It is strictly necessary to consult a doctor for interpreting the results correctly and even conduct follow-up tests if required.

Risks Of Vitamin B12 Test

Although there are no side effects or risk factors of a vitamin B12 test apart from a pricking feeling and slight soreness in the area where the needle is inserted. In certain cases, if a person is suffering from hemophilia, a blood test can lead to excessive bleeding.


Vitamin B12 is an extremely important vitamin necessary for the healthy functioning and development of the brain. Hence a test to measure the levels of vitamin B12 is highly beneficial in preventing a host of ailments including neural disorders, hyperlipidemia, heart problems, skin infections, headaches, and insomnia.