Ask Dr. K

June 4, 2012

Regular B12 injections counter effects of pernicious anemia

DEAR DOCTOR K: 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.

DEAR READER: 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.

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