Regular B12 injections counter effects of pernicious anemia

Q. For years, my pernicious anemia was misdiagnosed as depression. Now that I have an accurate diagnosis, I'd like to learn more about my condition.

A. The cause and treatment of pernicious anemia were discovered more than 80 years ago. 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 your body does not have adequate vitamin B12, your body does not produce enough red blood cells. This is called anemia.

There are many different causes of anemia. Severe, untreated B12 deficiency is called “pernicious” anemia because it damages the brain, spinal cord and nerves, as well as causing anemia, and can be fatal if not treated.

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 that has a red, beefy appearance

• nausea or poor appetite

• weight loss

If your B12 levels remain low for a long time, the condition can damage nerve cells. This can cause:

• numbness and tingling in the hands and feet

• muscle weakness

• irritability

• confusion

• depression

Some of the symptoms are similar to those of depression. This may help explain why you were misdiagnosed.

It can be tricky for the doctor to diagnose pernicious anemia. First, there are other conditions that can lower vitamin B12 levels. Second, pernicious anemia doesn't always cause anemia: In some people, it causes brain and spinal cord damage without causing anemia.

A simple blood test can measure vitamin B12 levels. Since other conditions can also cause low vitamin B12 levels, additional blood tests are necessary.

Treatment involves replacing the missing vitamin B12 with regular injections of the vitamin. 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 will need injections for the rest of your life to prevent symptoms from returning. Some people can take high doses of oral B12 instead of or to supplement injections.

I have high hopes for your recovery because pernicious anemia responds well to treatment. Before the Nobel Prize-winning discovery that pernicious anemia could be cured by vitamin B12, many people died of the disease. The good news is that you developed this condition in the 21st century, not 80 years ago, and that medical research has led to an effective treatment.

• Dr. Komaroff is a physician and professor at Harvard Medical School. Go to his website to send questions and get additional information: AskDoctorK.com.