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Pernicious Anemia: When You Can’t Absorb Enough Vitamin B12

Pernicious anemia is a type of anemia you could have if you can’t absorb enough vitamin B12. When that happens, your body doesn’t produce enough red blood cells. People over age 60 who are of northern European descent are more likely to have it, but it can affect anyone. Pernicious anemia is an autoimmune condition, and your risk is higher if you have other autoimmune disorders.

“You could develop pernicious anemia if you don’t have enough intrinsic factor, which is a protein that’s made in the lining of your stomach,” said Andrea Padilla, MD, a family medicine physician with Banner – University Medicine.

You need intrinsic factor to absorb health amounts of vitamin B12 and it’s usually an autoimmune condition that causes low levels of intrinsic factor. This happens when your body’s immune system attacks the cells in your stomach that produce intrinsic factor. Experts aren’t sure why this happens.

You’re also at higher risk if you have a family history of pernicious anemia. That’s because genetic factors could make you more likely to have less intrinsic factor or the autoimmune condition that causes it. 

In addition, some problems with your digestive system could cause pernicious anemia. They include medical conditions such as celiac disease, Crohn’s disease, gastric bypass surgery and other conditions that affect your stomach or small intestine. 

Who’s at risk?

You’re more likely to have pernicious anemia if you:

  • Are over age 60 and of Northern European or Scandinavian descent, although it also affects people from other ethnic backgrounds. 
  • Have autoimmune disorders such as type 1 diabetes, Hashimoto’s thyroiditis or Addison’s disease.
  • Have been exposed to certain chemicals or toxins, although more research is needed to establish this connection.

What are the symptoms?

The symptoms of pernicious anemia can vary in different people who have the condition, and they can change over time. “People often feel tired, have yellowed skin and may have neurologic abnormalities such as peripheral neuropathy or slowed cognition,” Dr. Padilla said.

You may notice:

  • Fatigue
  • Weakness
  • Pale skin
  • Shortness of breath
  • Dizziness
  • Numbness or tingling in the hands and feet
  • Difficulty concentrating
  • Mood changes

How pernicious anemia is diagnosed

Your health care provider will consider a range of factors to diagnose pernicious anemia. “A combination of tests is required,” Dr. Padilla said. They include:

  • Medical history and symptoms: Your provider will review your medical history and ask you about symptoms such as fatigue, weakness, pale skin, shortness of breath or tingling in the hands and feet. 
  • Physical examination: Your provider will check for signs of anemia, such as pale skin, a rapid heartbeat (tachycardia), an enlarged spleen, neurological symptoms or certain changes in your tongue. 
  • Blood tests: A complete blood count (CBC) measures your red blood cells, white blood cells and platelets. If you have pernicious anemia, the CBC may show a low level of red blood cells as well as abnormally large red blood cells (macrocytosis). Your levels of hemoglobin and hematocrit may also be low. 
  • Vitamin B12 levels: Another blood test can measure your levels of vitamin B12. Low levels of vitamin B12 could mean you have pernicious anemia. But other factors can also cause vitamin B12 deficiency, so you’ll need additional tests to confirm or rule out the condition. 
  • Intrinsic factor antibodies: An autoimmune reaction against the cells that produce intrinsic factor often causes pernicious anemia. So, your health care provider may order a test to check for intrinsic factor antibodies. People with pernicious anemia typically have these antibodies. 
  • Additional tests: In some cases, you could need more tests to confirm the diagnosis or rule out other possible causes of anemia. Your doctor may want to check your iron and folate levels and examine your bone marrow. 

How pernicious anemia is treated

The main treatment for pernicious anemia is vitamin B12 supplementation. “If you have pernicious anemia, you will need to take vitamin B12 for life,” Dr. Padilla said. You can usually take vitamin B12 as either a nasal spray or an injection. You’ll also need to regularly follow up with your health care provider to monitor your vitamin B12 levels. Your provider can adjust your treatment as needed.

You can’t treat pernicious anemia with diet alone. But a well-balanced diet rich in vitamin B12 can help you stay healthy and complement your treatment. You’ll find vitamin B12 in meat, fish, dairy products and fortified foods.

To support your overall well-being, it’s also a good idea to prioritize self-care. You’ll want to get regular physical activity, practice stress management techniques and maintain a healthy lifestyle. 

Complications of pernicious anemia

Diagnosing and treating pernicious anemia and having regular checkups can help you spot any complications or changes early. Untreated, it can cause:

  • Neurological problems: You need vitamin B12 so your nervous system can function as it should. When you don’t have enough vitamin B12, you can develop nerve damage. Symptoms include tingling or numbness in the hands and feet, difficulty walking, balance problems, memory loss, confusion and depression. “These issues can become permanent if pernicious anemia isn’t treated,” Dr. Padilla said.
  • Heart issues: Vitamin B12 helps your body produce red blood cells, which carry oxygen throughout the body. When you don’t have enough healthy red blood cells, you develop anemia. Severe or long-lasting anemia can strain your heart and cause palpitations, an irregular heartbeat or even heart failure. 
  • Cognitive impairment and dementia: Not having enough vitamin B12 can lead to problems with memory, concentration and overall cognitive abilities. Over time, your ability to think properly can decline, and you have a higher risk of developing conditions like Alzheimer’s disease. 
  • Pregnancy complications: Pernicious anemia can lead to complications for both mother and baby. Vitamin B12 is crucial for the healthy development of the fetus, and low levels increase the risk of preterm birth, low birth weight and developmental issues in the baby. Vitamin B12 is also essential for the mother’s health. Low levels increase the risk of complications such as gestational diabetes and preeclampsia. 
  • Increased risk of infections: Vitamin B12 helps your body produce white blood cells, which you need to fight off infections. When you don’t have enough vitamin B12, you’re more likely to get bacterial, viral and fungal infections. 
  • Higher risk of certain cancers: Chronic inflammation and changes in the stomach lining that come with pernicious anemia could make you more likely to develop gastric (stomach) cancer, particularly adenocarcinoma. However, the increased risk of cancer in people with pernicious anemia is low, and most people with it do not develop cancer. 

Connecting with support

You don’t have to face pernicious anemia alone. In addition to your health care team, you can connect with support groups, online communities and educational resources where you can find information, support and guidance. Here are some places to start:

The bottom line

Pernicious anemia is an autoimmune condition that is linked to low levels of vitamin B12. It can cause fatigue, yellow skin, neurological problems and other symptoms. But you can treat it with vitamin B12 supplementation and keep symptoms and complications to a minimum. 

If you would like to connect with a health care provider who can evaluate your symptoms and diagnose and treat pernicious anemia, connect with Banner Health.

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