Pernicious anemia is a form of megaloblastic anemia which is caused by an inability to absorb vitamin B12 properly. Megaloblastic anemias involve the red blood cells, and in the case of pernicious anemia, the red blood cells are depleted and they may be malformed. Historically, this condition was not identified until people were already experiencing symptoms of anemia, including complications, but today, it can be diagnosed with screening before anemia occurs. People with a family history of pernicious anemia should consider screening to see whether or not they are at risk.
There are a number of potential causes for pernicious anemia. One is a congenital form, in which a child is born without the ability to absorb vitamin B12. In other cases, an underlying disease process interferes with absorption of this vitamin. In patients with pernicious anemia, the stomach does not produce enough of a substance called intrinsic factor. Without intrinsic factor, the bowels cannot take up vitamin B12, and it is passed as a waste product, rather than being absorbed. Once the body has used up its reserves of vitamin B12 in the production of red blood cells, anemia starts to emerge.
Patients with this condition often have gastrointestinal problems in addition to classic symptoms of anemia such as weakness, lethargy, and pale skin. Pernicious anemia can be diagnosed with a blood test, and with a test in which B12 is injected and a test is done to see how much has been absorbed. Although this condition was once dangerous because it was identified late in many cases, today it is very treatable.
The treatment for pernicious anemia is B12 supplementation, to make sure that the body has enough of this vitamin. One of the best ways to do this is with periodic B12 injections straight into the muscle. If injections are not an option, a patient may be given B12 pills to take. If the symptoms are not resolved, additional testing can be performed to see if the supplementation doses need to be changed, and to check for other problems which may be causing anemia.
Also known as Addison-Biermer anemia, pernicious anemia tends to be more common in people of Northern European and African descent. Individuals who are at risk include older adults from these genetic backgrounds, people with a family history of the disease, and people with conditions such as diabetes. People who have had bowel resection surgeries or gastric bypasses are also at risk of pernicious anemia, in addition to deficiencies caused by the inability to properly absorb nutrients.