Pernicious Anemia: An Explanation

Q:  I have been diagnosed as having pernicious anemia and have been getting a B-12 shot once a month for the past year. However, I don't feel any different; I am always very tired, which is very different for me. Can you explain to me just what it is and what causes it? Is there anything else I can do?

A:  Pernicious anemia (PA) results from inadequate vitamin B12, which is necessary for making healthy red blood cells. In classic pernicious anemia the person lacks "intrinsic factor," a substance made by the stomach which binds to the B12 in food and enables the B12 to be absorbed. A person can get PA from a hereditary deficiency of intrinsic factor, surgical removal of portions of the stomach, chronic inflammation of the stomach lining (atrophic gastritis), and rarely from lack of B12 in the diet (mainly found in meat and dairy products).

After a year of B12 injections, your body stores should be more than adequate, so I suspect there is probably another reason to explain your fatigue other than pernicious anemia. Fatigue can be due to so many things that range from the trivial, such as this very hot, humid weather we've been having this summer, to the serious, such as cancer. If you don't "feel right," it's best to get checked out.

"Dear Doctor" is a compilation of patient questions answered by doctors from the Medical College of Wisconsin.