Pernicious anemia is a rare type of anemia (an inadequate number of red blood cells) that results from a lack of vitamin B12 (cobalamin), an essential component in the manufacture of red cells. In most cases, the condition isn’t due to a dietary deficiency of B12, which is very rare, and is seen only in strict vegetarians. Rather, this disorder usually occurs because the body cannot properly absorb the vitamin.

Pernicious anemia, which develops and progresses subtly, may at first produce the characteristic symptoms of any type of anemia: weakness, fatigue, and paleness (pallor). Untreated, the disease may cause disturbances in the gastrointestinal and cardiovascular systems and especially the nervous system, because B12 is essential for proper nerve function.

With treatment, prognosis is excellent, although severe neurologic damage from delayed treatment is usually permanent. People with pernicious anemia are at increased risk for other conditions, including autoimmune disorders, specifically those affecting the adrenal glands, thyroid, and parathyroid. Pernicious anemia can occur at any age; among younger individuals it is most common in African American women.

What Causes Pernicious Anemia?

  • Pernicious anemia almost always results from an impaired ability to absorb vitamin B12. This can occur when cells in the stomach lining atrophy and fail to produce normal amounts of digestive acids as well as a substance called intrinsic factor, which is essential for the absorption of B12.
  • The incidence of pernicious anemia is higher in those with a family history of pernicious anemia or other apparent autoimmune disorders, such as Graves’ disease, hypothyroidism, or vitiligo.
  • Surgical resection of the stomach, damage to the lining of the stomach, or prolonged treatment with stomach acid inhibitors may prevent secretion of intrinsic factor and hamper B12 absorption.
  • Disorders of the small intestine, where vitamin B12 is absorbed, can interfere with B12 absorption.
  • Pernicious anemia occurs without an intrinsic factor or another causes, such as infections, surgery, medicines and diet.
  • Rarely, a dietary lack of B12 causes the disorder.

Symptoms of Pernicious Anemia

  • Fatigue and weakness
  • Abdominal cramps
  • Imbalance, changes in reflexes, irritability, confusion and depression
  • Heart palpitations; lightheadedness or dizziness
  • Pallor (may be especially noticeable in the lips, gums, eyelids, and nail beds)
  • Shortness of breath or chest pain on exertion
  • Sore, red, and glazed-looking tongue
  • Irritability or inability to concentrate
  • Mild jaundice of the eyes or skin
  • Loss of appetite leading to weight loss
  • Nausea and diarrhea
  • Neurologic symptoms: numbness and tingling in the extremities, poor coordination, and loss of fine touch
  • Personality changes (megaloblastic madness)

Pernicious Anemia Prevention

  • There is no way to prevent pernicious anemia, except in the rare cases caused by a dietary B12 deficiency, which may affect strict vegetarians (vegans). Such people should take vitamin supplements.
  • Avoid self-medication with folic acid, which can mask the anemia of vitamin B12 deficiency.
  • Eat foods high in vitamin B12 to help prevent low levels of this vitamin.

Diagnosis of Pernicious Anemia

  • Patient history and physical examination.
  • A blood test to measure levels of serum B12 and red cell folate (the blood abnormalities of vitamin B12 and folate deficiency are identical).
  • A Schilling test, which involves swallowing radioactive vitamin B12 to accurately measure the amount being absorbed into the bloodstream and excreted in the urine.

Pernicious Anemia Treatment

  • Lifelong intramuscular injections of vitamin B12 (usually self-administered once a month) are necessary. Because the problem lies in the body’s inability to absorb the vitamin, oral B12 is generally not used. However, massive oral doses of B12 are effective when injections are not feasible.
  • Rarely, those with very severe anemia may need an initial blood transfusion.
  • Pernicious anemia is associated with an increased risk of stomach cancer, so lifelong cancer screening is recommended.

When to Call a Doctor

  • Consult your doctor if you experience persistent fatigue, weakness, or pallor.


Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference

Simeon Margolis, M.D., Ph.D., Medical Editor

Prepared by the Editors of The Johns Hopkins Medical Letter: Health After 50

Updated by Remedy Health Media

Publication Review By: the Editorial Staff at

Published: 16 Aug 2011

Last Modified: 02 Oct 2014