Pernicious anemia (PA) is a rare autoimmune condition where your body can’t make enough healthy red blood cells because it lacks vitamin B12. PA affects people of all ages, but mostly those over 60. It's just one of the causes of B12 deficiency. A long time ago, pernicious anemia was fatal (“pernicious” means "deadly"). These days it’s easily treated with B12 pills or shots. With treatment, you can live without symptoms.
What Causes Pernicious Anemia?
Your body needs plenty of healthy red blood cells. These carry oxygen to every part of your body. Without them, your tissues and organs don’t work properly.
Vitamin B12 is a crucial part of this process. If you have pernicious anemia, your body produces antibodies that destroy a stomach protein called “intrinsic factor” (IF). Without IF, vitamin B12 cannot be effectively absorbed from food. IF normally carries B12 from the food you eat to cells in your small intestine. From there, B12 normally makes its way to your bloodstream.
The antibodies also attack cells in the mucosal lining (moist inner lining) of your stomach and nerve cells. This stops the absorption of B12 as part of your immune system's response. This is why pernicious anemia is considered an autoimmune disease. It's not clear how you get PA, though genetic and environmental factors may play a role.
B12 is a vitamin found only in animal products such as meat and dairy, although sometimes breads and cereals are fortified with it. It plays an important role in keeping your blood and nerve cells healthy and in making DNA. Note that PA isn't caused by not eating foods that contain B12, but rather by your body's inability to absorb B12.
Some health issues make you more likely to have PA. These include:
- Autoimmune diseases, such as hypoparathyroidism, Graves’ disease, myasthenia gravis, and type 1 diabetes
- Crohn’s disease
- HIV
- Vitiligo
- Celiac disease
- Having part or all of your small intestine removed
- Small intestine bacterial overgrowth, a condition where you have harmful bacteria in your intestines that absorb all the B12 before your intestines can
Other risk factors for pernicious anemia include:
- Scandinavian or Northern European ancestry
- Family history of PA
- Having gastric bypass surgery (used to treat obesity), which loses cells that absorb B12
- Taking medications such as antacids or drugs that treat type 2 diabetes but make it harder for your body to absorb enough B12
Pernicious Anemia Symptoms
Symptoms of pernicious anemia may take years to develop because your body can store 1,000 to 2,000 times as much B12 as you need in a day. Here are some signs you have PA:
Early signs of pernicious anemia
- Fatigue (many people wake up tired despite getting enough sleep)
- Shortness of breath
- Feeling dizzy
- Loss of appetite
- Diarrhea or constipation
- Lightheadedness when standing up or moving around
- Pale or yellow skin (in people of European ancestry)
- Heartburn
- Swollen tongue
Long-term signs of pernicious anemia
- Short-term memory loss
- Trouble with balance (for example, struggling to put on your pants or socks while you’re standing)
- Burning feeling in your legs or feet that may get worse at night
- Depression
- Trouble focusing and confusion
- Cold hands and feet
- Hallucinations
- Eyesight problems
Pernicious anemia tongue
About 25% of people with pernicious anemia have symptoms on their tongues. Your tongue may look very smooth, have red patches, and be swollen. This is called atrophic glossitis. Your mouth might also feel sore and you might lose your sense of taste. Glossitis can be an early sign that you're lacking in B12 and you might have it even before you feel anemic.
Pernicious Anemia Tests
Your doctor will ask about your family history, as pernicious anemia can run in families. They’ll also want to know about your symptoms, the foods you often eat, and any medicines you take every day.
During a physical exam, your doctor will listen to your heart, check to see if your liver’s enlarged, and look for any signs of nerve damage. They may do tests that check your balance, how well you can walk, and your mental status.
Your doctor will also order blood tests. These could include:
Complete blood count (CBC). This reveals if you have a low level of hemoglobin. It’s the substance in red blood cells that helps carry oxygen throughout your body. Low levels of hemoglobin are a sign of anemia. The CBC also checks the size and shape of your red blood cells. Abnormal sizes and shapes can be signs of anemia.
B12 level. This measures how much vitamin B12 is in your body. A low level can mean pernicious anemia. Normal B12 levels are 400 picograms per milliliter. B12 deficiency is indicated by levels of 200 or lower.
Reticulocyte count. This test measures the number of young red blood cells in your blood to check whether your bone marrow is making new red blood cells.
Lactate dehydrogenase (LDH) test. LDH is an enzyme in your blood. High levels could mean a pernicious anemia diagnosis.
Homocysteine and methylmalonic acid (MMA) levels. High levels of either substance could be a sign of PA.
Intrinsic factor antibodies and parietal cell antibodies check. The presence of these antibodies indicates PA.
Serum folate and iron tests. These can show whether you have PA or another type of anemia.
Other tests could include:
Upper endoscopy. The doctor puts a thin tube with a lens down your throat to check for signs of deterioration in the lining of your stomach.
Bone marrow test. This checks whether your bone marrow is healthy and making enough red blood cells.
Pernicious Anemia Treatment
Vitamins you buy at the drugstore don’t have enough B12 in them to treat PA. Your doctor will need to give you a shot of B12. At first, you may need to have one every day or other day. After 2 weeks, you can reduce this to weekly injections for 1 to 2 months and then to monthly injections.
Once your levels are normal, you can switch to a B12 supplement. Extra B12 can be prescribed as a pill, nasal spray, nasal gel, injection, or medicine you put under your tongue. The pill or injection is preferred. Whatever method you choose, you'll have to take B12 supplements for life.
You may wonder how a pill or injection can help if your stomach is unable to properly absorb B12. Injectable B12 bypasses the digestive system and goes straight into your bloodstream. The oral B12 supplements are at higher dosages than the amount you'd get from food, which increases the likelihood that enough B12 will reach the bloodstream, even when absorption is compromised.
Studies have shown that at doses high enough to fully saturate intestinal B12 receptors, oral B12 is effective, despite a lack of intrinsic factor. However, not everyone can get by with the B12 pill. You'll need to be monitored to make sure you're absorbing enough B12. Otherwise, you may have to continue with injections.
Your doctor may also prescribe antibiotics if you have bacteria in your intestines that prevent your body from absorbing B12.
Pernicious Anemia Complications
If you don't get treatment for pernicious anemia, you could face the following complications:
- Higher risk of gastric cancer
- Fractures in the back, upper leg, and upper forearm
- Brain and nervous system problems that could become permanent
- A false-positive Pap smear because a B12 deficiency affects the way certain cells in the cervix look
Takeaways
Pernicious anemia (PA) is an autoimmune condition where your body can’t absorb vitamin B12 and so can't make enough healthy red blood cells. This can make you tired, short of breath, and dizzy, among other things. Treatment involves a daily shot of B12. Once your levels return to normal, you can usually switch to a B12 pill that you'll take for the rest of your life. With treatment, you should be able to lead a normal life.
Pernicious Anemia FAQs
What is the difference between pernicious anemia and B12 deficiency?
Pernicious anemia means your stomach isn’t making a protein called intrinsic factor, and so you can’t absorb vitamin B12 from your diet. B12 deficiency is a broader term. You may have vitamin B12 deficiency because of pernicious anemia or other reasons, such as taking certain medications, having certain health conditions, or drinking heavily. You may also have B12 deficiency if you follow a strict vegan diet and aren't eating enough foods with B12.
How long can someone live with pernicious anemia?
If you're treated for it and take your B12 supplements daily, you can live a normal lifespan. Until the 1920s, there was no treatment for PA and people did die young after many years of illness. Thanks to the availability of treatment, that is a thing of the past.
Can pernicious anemia be cured?
It can't be cured. However, it can be managed by taking B12 supplements daily.
Who suffers most from B12 deficiency?
People over 60 are most likely to have B12 deficiency. Almost 20% of people over 60 in the U.S. and U.K. are B12-deficient compared to just 6% of people under 60, according to studies. In developing countries, B12 deficiency is much higher. Studies have shown that 70% of Kenyan schoolchildren, 70% of East Indian adults, and 40% of Latin American residents are B12 deficient.
What organ is affected by B12 deficiency?
Your brain and nervous systems are most affected, giving rise to symptoms such as fatigue, confusion, depression, loss of balance, and even hallucinations.
How can I raise my B12 levels fast?
If it's due to diet, you can eat more red meat, chicken, fish, and dairy. But if it's due to pernicious anemia, your doctor will need to inject you with vitamin B12.