Pernicious anemia, one of the causes of vitamin B12 deficiency, is an autoimmune condition that prevents your body from absorbing vitamin B12. Left untreated, pernicious anemia can cause serious medical issues, including irreversible damage to your nervous system.
Pernicious (per-nish-uhs) anemia, one of the causes of vitamin B12 deficiency, is an autoimmune condition that prevents your body from absorbing vitamin B12. Without adequate vitamin B12, you have fewer red blood cells carrying oxygen throughout your body. You can have pernicious anemia for several years before noticing changes in your body. Left untreated, pernicious anemia can cause serious medical issues, including irreversible damage to your nervous system. Healthcare providers treat pernicious anemia by prescribing vitamin B12 supplements.
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The term “pernicious” means harmful, and pernicious anemia causes harm to several body systems:
Pernicious anemia typically affects people aged 60 to 80 of Northern European descent. Pernicious anemia is estimated to affect 151 in 100,000 people in the United States.
Generally speaking, the longer you go without adequate vitamin B12, the more serious your symptoms are. Early on, people may have mild symptoms they may think are caused by other common conditions. Examples include:
Long-term low vitamin B12 levels caused by pernicious anemia can affect your nervous system. Symptoms of potential nervous system problems include:
Yes. Normally, your body stores vitamin B12 that it gets from what you eat. Your body stores vitamin B 12, slowly using it over time. It can take three to five years for your body to use up your vitamin B12 reserves. After that, it can be several more years before you develop pernicious anemia symptoms.
Pernicious anemia is an autoimmune condition that happens when your immune system produces antibodies that attack cells in the mucosal lining of your stomach and nerve cells. Your immune system’s response affects your body’s ability to absorb vitamin B12.
The antibodies also block a critical protein called intrinsic (in-TRIN-sic) factor. Normally, intrinsic factor carries the vitamin B12 we get from food to special cells in your small intestine. From there, the vitamin B12 is transported into your bloodstream. Other proteins then carry the vitamin B12 to your bone marrow, where the vitamin is used to make new red blood cells. This process can’t happen when your immune system blocks your intrinsic factor.
You may also develop vitamin B12 deficiency if:
First, your healthcare provider will complete a thorough physical examination and ask questions about your medical history so they know if you’ve any other conditions that may increase your risk of vitamin B12 deficiency. They may ask you if you’re having trouble concentrating. They may look for signs of nervous system problems. Other tests they may do include:
Since vitamin B12 absorption is blocked, your healthcare provider may prescribe intramuscular vitamin B12 injections. Later, after B12 stores are back to normal, they may prescribe high doses of oral B12 replacement. They’ll monitor your treatment. They may prescribe antibiotics if you have bacteria in your intestine that prevents your body from absorbing vitamin B12.
Many people begin feeling better a few days after starting treatment. But you may need a few weeks of regular treatment before you notice significant changes and your condition improves.
Everyone’s situation is different, but most people who have pernicious anemia take vitamin B12 supplements for the rest of their lives.
You can’t prevent pernicious anemia from occurring. But you can reduce your risk by being aware of medical conditions, treatments and activities that may affect your body’s ability to absorb vitamin B12. If you’re concerned about pernicious anemia, ask your healthcare provider if you’re at risk and what steps you can take to avoid vitamin B12 deficiency.
Most people begin feeling better shortly after starting treatment. Pernicious anemia can’t be cured, but increasing your vitamin B12 intake may eliminate most symptoms. The neurologic complications of pernicious anemia, however, can persist even after B12 stores are fully replaced. If that’s your situation, ask your healthcare provider about other treatments that may ease your symptoms.
If you have pernicious anemia, you’ll need to take vitamin B12 supplements regularly for the rest of your life. Other causes of B12 deficiency may be helped by increasing the vitamin B12 in your diet. Some foods to consider adding to your diet include:
Your healthcare provider may recommend regular appointments so they can monitor your vitamin B12 supplements, your B12 levels and your general health.
Pernicious anemia symptoms can take years to surface. You may be surprised to learn you have a condition that can cause serious medical problems. Here are some questions you may want to ask your healthcare provider:
You can develop vitamin deficiency anemia if your diet doesn’t include enough vitamin B6 or folic acid.
A note from Cleveland Clinic
Pernicious anemia can sneak up on you. You can have this disease for many years before you notice changes in your body that happen because you’re not getting enough vitamin B12. Early pernicious anemia symptoms are mild — so mild that some people simply learn to live with feeling tired, lightheaded or breathless. But diagnosing pernicious anemia early can prevent serious and irreversible problems with your nervous system. You know your body best. If you’re feeling weak and unusually tired, talk to your healthcare provider. If you’re diagnosed with pernicious anemia, they’ll prescribe treatment to restore normal vitamin B12 levels and treat your anemia.
Last reviewed by a Cleveland Clinic medical professional on 02/07/2022.
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