Vitamin B12 Deficiency

Dr. Anurag Shahi (AIIMS)MBBS,MD

January 15, 2019

March 06, 2020

Vitamin B12 Deficiency
Vitamin B12 Deficiency

What is Vitamin B12 deficiency?

Vitamin B12 is also known as cyanocobalamin and plays a vital role in cellular metabolism, particularly DNA synthesis and energy production. Vitamin B12 is absorbed in the small intestine after combining with a factor called the intrinsic factor that is released from the stomach. The deficiency of vitamin B12 causes the body to produce abnormal red blood cells leading to megaloblastic anaemia. Apart from this, it hampers transmission of nerve impulses and affects many other tissues like the hair follicle, spinal cord, etc.

What are the main associated signs and symptoms?

The early symptoms are mentioned below:

The severe symptoms are as follows:

What are the main causes?

Some of the causes of the deficiency are mentioned below:

  • An autoimmune condition called pernicious anaemia that results in malabsorption of B12 in the intestine
  • A family history of pernicious anaemia
  • Lack of vitamin B12-rich foods in diet, such as fish, eggs, meat, and mushrooms
  • Insulin and acidity medications that prevent adequate production of intrinsic factor in the stomach
  • Surgical removal of the stomach or intestines
  • Severe diseases of intestines like inflammatory bowel diseases
  • Cancer
  • Pregnancy

How is it diagnosed and treated?

A general examination of the patient, which involves a physical assessment of symptoms along with a detailed history helps diagnose the condition.

Blood tests include

  • Haemoglobin levels – Less haemoglobin levels indicate anaemia
  • Vitamin B12 levels
  • Picture of red blood cells – Larger size of blood cells indicate a deficiency
  • Measurement of indicators of B12, i.e., serum homocysteine or methylmalonic acid
  • Schilling test to detect pernicious anaemia

The treatment modalities include

  • Supplementation of oral or injection vitamin B12
  • Dietary changes to include more foods that are rich in vitamin B12.


  1. Fiona O’Leary,Samir Samman. Vitamin B12 in Health and Disease. Nutrients. 2010 Mar; 2(3): 299–316. PMID: 22254022
  2. Green R et al. Vitamin B12 deficiency . Nat Rev Dis Primers. 2017 Jun 29;3:17040. PMID: 28660890
  3. Oh R,Brown DL. Vitamin B12 deficiency. Am Fam Physician. 2003 Mar 1;67(5):979-86. PMID: 12643357
  4. Langan RC,Zawistoski KJ. Update on vitamin B12 deficiency. Am Fam Physician. 2011 Jun 15;83(12):1425-30. PMID: 21671542
  5. Wolfgang Herrmann et al. Causes and Early Diagnosis of Vitamin B12 Deficiency. Dtsch Arztebl Int. 2008 Oct; 105(40): 680–685. PMID: 19623286
  6. National Institutes of Health; Office of Dietary Supplements. [Internet]. U.S. Department of Health & Human Services; Vitamin B12.

Doctors for Vitamin B12 Deficiency

Dr. Narayanan N K Dr. Narayanan N K Endocrinology
16 Years of Experience
Dr. Tanmay Bharani Dr. Tanmay Bharani Endocrinology
15 Years of Experience
Dr. Sunil Kumar Mishra Dr. Sunil Kumar Mishra Endocrinology
23 Years of Experience
Dr. Parjeet Kaur Dr. Parjeet Kaur Endocrinology
19 Years of Experience
Consult a Doctor

Medicines for Vitamin B12 Deficiency

Medicines listed below are available for Vitamin B12 Deficiency. Please note that you should not take any medicines without doctor consultation. Taking any medicine without doctor's consultation can cause serious problems.

Lab Tests recommended for Vitamin B12 Deficiency

Number of tests are available for Vitamin B12 Deficiency. We have listed commonly prescribed tests below: