DEAR DOCTOR K:
My new doctor recently told me I had pernicious anemia, that it had not been diagnosed by my old doctor and that his treatments would end my symptoms. What is pernicious anemia?
The cause and treatment of pernicious anemia were discovered more than 80 years ago, here at Harvard Medical School. The discovery was honored with the Nobel Prize. Unfortunately, even today there still are people like you for whom diagnosis and treatment have been delayed. That’s because, as I explain below, it can be a tricky condition to diagnose.
With pernicious anemia, vitamin B12 cannot be absorbed by the intestines. Your body needs vitamin B12 to produce healthy red blood cells. When it does not have adequate vitamin B12, your body does not produce enough red blood cells (anemia). Pernicious anemia also damages the brain, spinal cord and nerves, and can be fatal if not treated.
Pernicious anemia is an autoimmune disease in which the immune system mistakenly attacks some part of the body as if it were foreign. In pernicious anemia, the immune system makes antibodies against a normal substance in the gut called intrinsic factor (IF). IF is necessary for vitamin B12 in the diet to be absorbed into the body.
Symptoms of pernicious anemia tend to develop slowly and can be subtle. As the condition worsens, you may experience:
- weakness and fatigue;
- lightheadedness and dizziness;
- palpitations and rapid heartbeat;
- shortness of breath;
- a sore tongue with a red, beefy appearance;
- nausea or poor appetite;
- weight loss.
The nerve damage can cause:
- numbness and tingling in the hands and feet;
- muscle weakness;
A simple blood test can measure vitamin B12 levels. Since other conditions can also cause low vitamin B12 levels, additional blood tests are necessary to make the diagnosis of pernicious anemia. These include antibodies against IF, gastrin and pepsinogen.
Treatment involves replacing the missing vitamin B12 with regular injections of the vitamin. (Some people are able to use mega-doses of B12 in pill form, but treatment is usually by injections.) Your body will quickly produce new red blood cells, and your symptoms should begin to improve within 72 hours.
Once your B12 reserves reach normal levels, you will need vitamin B12 injections every one to three months. You probably will need injections for the rest of your life to prevent symptoms from returning.
I have high hopes for your recovery because pernicious anemia responds well to treatment. Before the discovery that it could be cured by vitamin B12 injections, many people died of the disease. Research here at Harvard and elsewhere has made it a curable disease.