Definition | Causes | Risk Factors | Symptoms | Diagnosis | Treatment | Prevention

Definition

Vitamin B12 deficiency can occur when the body needs more vitamin B12 than it receives from the diet. Alternatively, the condition may occur when the body is unable to use the vitamin B12 from the diet. A shortage of vitamin B12 can lead to anemia. Anemia is the insufficient delivery of oxygen by red blood cells from the lungs to the cells of the body. The sooner this anemia is treated, the more favorable the outcome. If you suspect you have this condition, contact your doctor immediately.

Red Blood Cells

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Causes

There are many causes of vitamin B12 deficiency. Some are listed below.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition. The following factors increase your chance of developing vitamin B12 deficiency. If you have any of these risk factors, tell your doctor:

  • Alcoholism
  • Use of certain drugs:
    • Biguanides for diabetes
    • Para-aminosalicylic acid for tuberculosis
    • Calcium-chelating drugs taken by mouth
    • Colchicine
    • Neomycin
    • Cimetidine
    • Cholestyramine
  • Age: over 50 years old
  • Strict vegan or vegetarian diet

Symptoms

The symptoms of pernicious anemia can vary from person-to-person. Symptoms may change or worsen over time. If you experience any of these symptoms, do not assume it is due to this anemia. These symptoms may be caused by other health conditions. If you experience any one of them, see your physician.

Symptoms can include:

Diagnosis

Your doctor will ask about your symptoms and medical history, and perform a physical exam. Tests may include the following:

  • Complete blood count (CBC)—a count of the number of red and white blood cells in a blood sample
  • Vitamin B12 level—a test that measures the amount of vitamin B12 in the blood
  • Methylmalonic acid (MMA) level—a measurement of the amount of methylmalonic acid in the blood; this test determines whether a vitamin B12 deficiency exists.
  • Homocysteine level—a test that measures the amount of homocysteine in the blood (homocysteine is a building block of protein). The homocysteine level will be elevated if there is a shortage of vitamin B12, folate, or vitamin B-6.
  • Schilling test—a test in which a harmless amount of radiation is used to assess whether a vitamin B12 deficiency exists (rarely used)
  • Red blood cell folate level—a measurement of the amount of a B vitamin called folate
  • Gastrin level—a test that may help determine the cause of a vitamin B12 deficiency
  • Intrinsic factor assay—a measurement of the amount of a protein called intrinsic factor normally produced in the stomach; this test helps to rule out pernicious anemia as the cause of symptoms.
  • Bone marrow staining—a test that shows whether an iron deficiency exists

Treatment

Talk with your doctor about the best treatment plan for you. Treatment options include the following:

This treatment consists of high doses of an oral vitamin B12 supplement.

The doctor may advise the patient to receive injections of vitamin B12 into a muscle. Injections of vitamin B12 may be given 2-4 days per week. When blood tests show improvement, the doctor may give injections on a monthly basis.

This type of medication may be needed in cases where bacterial overgrowth in the intestines exists. The bacteria compete with the body to absorb the vitamin B12 in the intestines.

The doctor gives the patient a supplement of vitamin B12 that is placed in the nose.

The physician will recommend this treatment when an iron deficiency exists. In this case, the doctor will tell the patient to take iron supplements before treating with vitamin B12.

Prevention

To help reduce your chances of developing a deficiency of vitamin B12, take the following steps:

  • Avoid long-term over-consumption of alcohol.
  • As directed by your doctor, take a daily supplement containing vitamin B12.
    • As directed by your doctor, give vitamin B12 to your breastfed baby if you are a vegan or vegetarian.
  • Avoid overuse of nitrous oxide.
  • Seek diagnosis and treatment of any suspected tapeworm infestation.
  • Have your doctor check you for iron deficiency.
  • Undergo testing if your doctor suspects you are infected with the bacterium Helicobacter pylori.
  • Have your doctor monitor your health closely if you are taking the following drugs:
    • Biguanides
    • Aminosalicylic acid
    • Calcium-chelating drugs taken by mouth
    • Colchicine
    • Neomycin
    • Cimetidine
    • Cholestyramine