Pernicious Anemia

Pernicious anemia is a condition in which the body does not make enough red blood cells due to a lack of vitamin B12 in the body. It usually occurs in people whose bodies have lost the ability to absorb vitamin B12 from food.

Anemia

Pernicious anemia is one of many different types of anemia. Having anemia means you do not have enough healthy red blood cells. When a person has anemia, the blood cannot carry enough oxygen to the cells of the body. The most common symptom of anemia is feeling tired.

Pernicious Anemia

In pernicious anemia, the blood cells do not divide normally and are too large. They have trouble getting out of the bone marrow. The problem is due to a lack of vitamin B12 in the body. Vitamin B12 is one of the B vitamins; B vitamins are found in animal foods such as meat, fish, eggs, milk, and other dairy products. Vitamin B12 is necessary for the body to make red blood cells. It is also needed for the normal working of the nervous system.

People can develop low levels of this important vitamin in three main ways:

• From the lack of a protein in the stomach that helps the body absorb vitamin B12. The protein is called intrinsic (in-TRIN-sik) factor. Intrinsic factor is made by special cells in the lining of the stomach. In some people, these cells are destroyed by the body’s immune system or as a result of stomach surgery. When this happens, intrinsic factor is not produced and vitamin B12 cannot be absorbed. This is the most common cause of vitamin B12 deficiency.
• From not getting enough vitamin B12 in the diet. This can be the result of eating a strict vegetarian diet or a poor diet due to factors such as aging or alcoholism.
• From certain intestinal disorders that interfere with the absorption of vitamin B12, such as Crohn’s disease and intestinal infections.

The condition was named "pernicious" anemia because it was often fatal in the years before the cause was discovered to be a lack of vitamin B12, and no specific treatments were available. Now it is easy to treat with vitamin B12 pills or injections. Pernicious anemia can be severe if it goes on for a long time without being treated. If it is not treated, it can cause permanent damage to the body. Pernicious anemia is especially common in older adults.

Effects of Pernicious Anemia on the Body

People who have pernicious anemia often feel tired and weak because the body is not getting enough oxygen. Over time, if untreated, this disease can cause serious problems for the heart, nerves, and other parts of the body.

Heart. In people with anemia, the heart has to work harder to pump blood to get enough oxygen to the body’s organs and tissues. This stress on the heart can cause heart murmurs (an extra or unusual sound heard during the heartbeat), fast or irregular heartbeats, an enlarged heart, or even heart failure.

A lack of vitamin B12 or folic acid (folate) can cause extra problems for the heart because it raises the level in the body of a chemical called homocysteine (ho-mo-SIS-teen). High levels of homocysteine add to the buildup of fatty deposits in blood vessels, which in turn can lead to heart attacks and strokes.

Nerves. A lack of vitamin B12 can damage nerve cells and cause problems such as tingling and numbness in hands and feet and problems with walking and balance. A vitamin B12 deficiency can cause changes in taste, smell, and vision. Finally, it can cause mental changes, including memory loss and confusion.

Digestive tract. A lack of vitamin B12 may change the surface of the tongue and shrink or thin the stomach lining. Any changes that occur in the stomach can put a person at risk for stomach cancer.

Outlook

Pernicious anemia is usually easy to treat with vitamin B12 pills or shots, although some people develop permanent nerve damage before they find out they have the disease and get treatment. Since pernicious anemia does increase the risk of developing stomach cancer, doctors may do periodic cancer tests to check for it. Overall, however, people with pernicious anemia who get proper lifelong treatment can have a normal lifespan.

Symptoms

Major Signs and Symptoms

Major signs and symptoms of pernicious anemia are feeling tired and weak and having a bright red, smooth tongue. Common symptoms of nerve damage caused by this disease are tingling and numbness in the hands and feet.

Symptoms most often develop slowly over time if the disease is not treated. Some people may experience mental changes and nerve problems before blood tests show that they have anemia. This is more likely to happen in older adults than in younger people.

Other Signs and Symptoms

Other signs and symptoms of pernicious anemia may include pale or yellowish skin, a low-grade fever, and dizziness when standing up. Infants with the condition may show unusual movements or a delayed development and failure to thrive.

Signs and Symptoms of Complications Associated With Pernicious Anemia

Complications seen with pernicious anemia can involve the heart, nerves and brain, and digestive tract. Some of the complications are due to the anemia; others are the effect of a low vitamin B12 level on parts of the body.

Heart

Signs and symptoms of heart problems may include shortness of breath and chest pain. Heart murmurs, a rapid heart rate, and heart failure can develop.

Nerves and Brain

In addition to tingling or numbness in the hands and feet, signs and symptoms of problems with the nerves may include difficulty walking, unsteady movement, and loss of balance. There can be changes in vision, taste, and smell. Memory loss, confusion, depression, and even psychosis can develop.

Digestive Tract

Signs and symptoms of untreated pernicious anemia can occur all along the digestive track. They can start with a bright red, smooth tongue and may include mouth sores or bleeding gums. The liver could be enlarged. Nausea and vomiting may occur, along with a sense of fullness, gas, or heartburn. Changes in bowel habits could include constipation or diarrhea. A person might have a loss of appetite or weight loss.

Diagnosis

Pernicious anemia is diagnosed using a person’s medical history, physical exam, and tests that can determine the type and cause of anemia. A doctor can use these methods to find out how severe the problem is, its cause, and the appropriate treatment. Mild to moderate anemia may have no signs or symptoms. In fact, anemia is often discovered unexpectedly on screening tests.

Major Causes

Pernicious anemia is caused by a lack of vitamin B12 in the body. The main reason for the vitamin B12 deficiency is the loss of parietal (pa-RI-e-tal) cells in the lining of the stomach. These cells make intrinsic factor, which helps the body absorb vitamin B12 in the small intestine. In some people, the body’s immune system may attack and destroy the parietal cells. Doctors don’t know exactly why or how this happens, or if the immune system produces antibodies in reaction to normally aging or dying parietal cells.

As a result of this immune system attack, the stomach lining shrinks, and the parietal cells in the lining of the stomach disappear. The stomach stops producing intrinsic factor. Over time, vitamin B12 deficiency develops.

Loss of intrinsic factor can also be due to removal of the stomach lining in various kinds of stomach surgery. This surgery includes removal of all or part of the stomach as well as stomach surgery for weight loss.

There is also a rare inherited disorder in which children are born without the ability to produce intrinsic factor.

Other Causes

Less common causes of pernicious anemia include a diet low in vitamin B12, intestinal problems, and certain medicines.

Lack of Vitamin B12 in the Diet

People can develop pernicious anemia if they don’t get enough vitamin B12 in the foods that they eat. This condition takes many years to develop because it takes time to use up the vitamin B12 already stored in the body.

Some people who are strict vegetarians can develop pernicious anemia, especially if they do not eat meat, poultry, fish, eggs, or dairy products?the best food sources of vitamin B12. Breastfed infants of strict vegetarian mothers can develop anemia in a short time because they don’t have enough vitamin B12 stored in their bodies. They can be given vitamin B12 supplements to prevent this type of anemia.

Some people develop pernicious anemia because of a poor diet due to conditions such as alcoholism or aging.

Disorders of the Small Intestine

Some intestinal problems can cause poor absorption of vitamin B12. These problems include:

• An infection caused by parasites or an overgrowth of bacteria in the intestine
• Celiac disease (also known as sprue), a genetic disorder that makes a person unable to tolerate gluten
• Crohn’s disease, an inflammatory bowel disease
• Not enough stomach acid to digest food—a problem that can occur in older adults

Medicines

Long-term use of certain medicines may lead to pernicious anemia. Examples of these are medicines that reduce acid in the stomach and certain diabetes medicines (such as metformin, phenformin, and biguanides).

Treatment

How Is Pernicious Anemia Treated?

Doctors treat pernicious anemia by replacing the missing vitamin B12 in the body. People who have pernicious anemia need treatment, usually for the rest of their lives. Without treatment, pernicious anemia can cause serious problems and can even be fatal.

Goals of Treatment

The goals of treating pernicious anemia are to:

• Stop the anemia and symptoms through vitamin B12 treatment
• Prevent complications, such as heart or nerve damage
• Provide ongoing followup to make sure that the treatment is working
• Treat the underlying cause, if one can be found

Specific Types of Treatment

Fortunately, pernicious anemia is usually easy to treat with either vitamin shots (injections) or pills. Symptoms may begin to improve within a few days after the start of treatment.

• Vitamin B12 shots. People with pernicious anemia may get daily or weekly shots at first, then one shot every month. Some people get vitamin B12 shots and also take vitamin B12 pills.
• Vitamin B12 pills. Many people with pernicious anemia can be treated successfully with vitamin B12 pills. Often, the pills work as well as the shots. Because only a small amount of vitamin B12 is absorbed by the body, high doses are given.

Vitamin B12 can also be given in a gel or spray for the nose.

Treatment for the underlying causes of vitamin B12 deficiency may be needed. To help the body absorb vitamin B12, for example, a person might need antibiotics to treat stomach infections or surgery to treat intestinal problems. If the vitamin B12 level is due to a poor diet, then a person can learn how to correct the diet.

The doctor may also recommend limiting physical activity until anemia symptoms have improved.

Reference:

National Heart, Lung, and Blood Institute, USA.