Dear Doctor Column, November 26, 2001

Question:

What is the difference in pernicious anemia and B-12 deficiency? What causes this condition? I am a 48-year-old woman and have been diagnosed with B-12 deficiency. I currently give myself B-12 injections every two weeks, but this doesn't seem to be effective and I have been experiencing severe leg pain and some blurred vision. What should I do?

Answer:

Pernicious anemia results from a deficiency of vitamin B-12 in the body. B-12 is essential for the production of red blood cells - the cells that carry oxygen to body tissues. Without enough B-12, red blood cell production decreases, and those cells that are formed are defective. Vitamin B-12 also is vital to the maintenance of the nervous system, and a deficiency can damage the brain, nerves and spinal cord.

Nearly everyone's diet contains enough vitamin B-12, which is plentiful in foods of animal origin, such as meat, fish, poultry, shellfish, milk, cheese and eggs. Just one cup of milk a day will meet your body's requirement for B-12. Vegetarians who avoid dairy products as well as meat may not get enough B-12 and need to take supplements or drink soy milk fortified with vitamin B-12.

The cause of pernicious anemia is not a lack of vitamin B-12 in the diet, but rather the inability of the digestive tract to absorb the vitamin from the intestine. The stomach fails to secrete enough of a substance called intrinsic factor, which must bind with B-12 before it can be absorbed in the small intestine.

Pernicious anemia causes fatigue, lightheadedness, shortness of breath and a fast heartbeat, particularly upon exertion. A sore mouth and tongue may occur, and the skin may become pale or yellow in color. Damage to the nerves caused by a lack of vitamin B-12 cause numbness and tingling in the hands and feet, problems with balance and, eventually, difficulty walking. Memory loss, confusion, depression, loss of appetite and weight loss, can also occur.

Pernicious anemia was often fatal before doctors discovered the cause and developed an effective treatment. Today, the disease can be treated with vitamin B-12 shots. The injected B-12 bypasses the stomach and intestine, circumventing the need for intrinsic factor. Once people are diagnosed with pernicious anemia, vitamin injections are required for life.

Normally, once B-12 injections are started, the anemia resolves, relieving the lightheadedness, fatigue and shortness of breath. The neurological problems, such as numbness in the fingers and toes, forgetfulness and unsteady gait, also can improve for up to a year. Unfortunately, permanent damage to the nerve cells in the spinal cord and elsewhere sometimes occurs before pernicious anemia is diagnosed and treated.

Pernicious anemia is not common and most often appears in people age 60 and older. For unknown reasons, the onset of the disease in African Americans occurs at a much younger age. Except for an extremely rare form of the disease, pernicious anemia is not hereditary.

You should make an appointment with your physician right away to discuss your leg pain and blurred vision.