Pernicious anemia develops when the body is unable to absorb the vitamin B12 it needs from food because of a lack of a protein, called intrinsic factor, produced by the stomach. Intrinsic factor is required for absorption of vitamin B12. Pernicious anemia is often associated with an autoimmune-mediated attack of parietal cells of the stomach and/or intrinsic factor. Anemia is the insufficient delivery of oxygen by red blood cells from the lungs to the cells of the body. The sooner pernicious anemia is treated, the better the outcome. If you suspect you have this condition, contact your doctor.

There are many possible causes of pernicious anemia. Some are listed below.

• Atrophic gastritis (inflammation of the stomach)
• Removal of all or part of the stomach
• Immune system reaction to:
  • Intrinsic factor—a protein necessary for vitamin B12 absorption
  • Cells that produce both intrinsic factor and hydrochloric acid in the stomach
• Genetics

A risk factor is something that increases your chance of getting a disease or condition.

The following factors increase your chance of developing pernicious anemia:

• Autoimmune disorders and other conditions, such as:
  • Type 1 diabetes
  • Addison’s disease
  • Graves’ disease
  • Myasthenia gravis
  • Secondary amenorrhea
  • Hypoparathyroidism
  • Hypopituitarism
  • Testicular dysfunction
  • Chronic thyroiditis
  • Vitiligo
  • Idiopathic adrenocortical insufficiency
• Ancestry: northern European or Scandinavian
• Age: over 50 years old

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 pernicious anemia. These symptoms may be caused by other health conditions. If you experience any one of them, see your physician. Symptoms can include:

• Sensation of pins and needles in feet or hands
• Alternating constipation and diarrhea
• Stinging sensation on the tongue, or a smooth red tongue
• Substantial weight loss
• Inability to distinguish the colors yellow and blue
• Tiredness
• Paleness
• Loss of hunger
• Altered sense of taste
• Confusion
• Depression
• Impaired sense of balance, especially in the dark
• Ringing in the ears
• Cracked lips
• Fever
• Inability to sense vibrations in feet or legs
• Dizziness when changing to standing position
• Rapid heart rate

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)
• Schilling test—a test in which a harmless amount of radiation is used to assess the amount of stored vitamin B12 (rarely used)
• Red blood cell folate level—a measurement of the amount of a B vitamin called folate
• Intrinsic factor assay—a measurement of the amount of a protein called intrinsic factor normally produced by the stomach
• Bone marrow staining—a test that shows whether an iron deficiency exists

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

The treatment consists of injections of vitamin B12 into a muscle. These injections are necessary because the intestines cannot absorb enough vitamin B12 without an adequate supply of intrinsic factor from the stomach.

If you are elderly, your doctor may advise you to take oral B12 supplements alone or in addition to injections of vitamin B12.

Your doctor may give you a supplement of vitamin B12 that is placed in the nose.

This treatment is recommended when an iron deficiency exists. In this case, the doctor will tell you to take iron supplements before treating with vitamin B12.