Pernicious anemia is a condition in which the body does not make enough red blood cells (erythrocytes) 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.
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.
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:
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 bodyPeople 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. 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.
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.
What causes pernicious anemia?
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 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.
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:
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).
Who is at risk for pernicious anemia?
People of all races can develop pernicious anemia. However, people of northern European or African descent have a higher risk than other races and ethnic groups.
Men and women in the United States are equally likely to develop the disease. It is more common in older adults than younger people, and it is rare in children.
Major risk factors
A person's chances of developing pernicious anemia may be higher if he or she has:
Pernicious anemia is more likely to develop in people who do not eat foods high in vitamin B12 for long periods of time. This includes some vegetarians, elderly people, and people with alcoholism.
What are the signs and symptoms of pernicious anemia?
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.
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.
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.
How is pernicious anemia diagnosed?
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.
Primary care doctors, such as a family doctor, often diagnose and treat pernicious anemia. Other kinds of doctors may also be involved, including:
Medical and family history
Your doctor may ask detailed questions about many symptoms, including feeling tired and weak and others listed in the section What Are the Signs and Symptoms of Pernicious Anemia? The doctor may ask about any personal or family history of anemia, diabetes, or diseases of the immune system. You may be asked about any surgery you have had, especially stomach surgery. The doctor may also ask you about your diet and about the medicines you are taking.
A physical exam may include:
Your doctor will also order a number of tests or procedures to be sure about the type of anemia you have and how severe it is.
Diagnostic tests and procedures
Complete blood count
Usually, the first test used to diagnose anemia is a complete blood count (CBC). The CBC tells a number of things about a person's blood, including:
The CBC also checks:
Tests to check the vitamin B12 level
Other blood tests
Other blood tests check for:
The Schilling test is a urine test that measures how well the body absorbs vitamin B12. It is not used as much now as it was in the past.
Bone marrow tests
In some cases, a doctor may want to do a bone marrow biopsy or aspiration. A bone marrow biopsy is a minor surgical procedure to remove a small amount of bone marrow tissue. In a bone marrow aspiration, the doctor removes a small amount of bone marrow fluid through a needle. Bone marrow biopsy or aspiration tests whether the bone marrow is healthy and can show whether the bone marrow is making enough blood cells.
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:
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 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.
How can pernicious anemia be prevented?
Doctors do not know how to prevent pernicious anemia that occurs from the immune system destroying parietal cells in the stomach. The most common cause of pernicious anemia is the loss of stomach cells that make intrinsic factor.
Pernicious anemia due to a diet low in vitamin B12 is not common. But some people who are strict vegetarians or who have a poor diet for a long time can develop this condition. Eating foods high in vitamin B12 and folic acid can help prevent low vitamin B12 levels. Some of these foods are:
Vitamin B12 also can be found in multivitamins and in B-complex vitamin supplements.
Doctors may recommend supplements for people at risk of developing vitamin B12 deficiency, such as infants and children of strict vegetarians.
Living with peripheral arterial disease
People treated for pernicious anemia can recover, feel well, and live normal lives, although they must be sure to receive enough vitamin B12 throughout their lives. If a person has developed health problems caused by pernicious anemia, such as nerve damage, treatment may reverse the damage.
Ongoing health care needs
People with pernicious anemia usually need to see a doctor regularly for checkups and ongoing treatment with vitamin B12. If you are being treated for pernicious anemia, you will need to take vitamin B12 supplements as directed by your doctor to prevent the return of symptoms.
Visits to the doctor will focus on monitoring for signs of vitamin B12 deficiency in your body, making treatment changes as needed, and checking for the possible development of stomach cancer.
Doctor visits will also focus on the foods that you eat and whether you
are eating enough foods that contain vitamin B12. A pediatrician
may prescribe vitamin B12 supplements for infants and children
of strict vegetarians.
Continued treatment may be needed for any ongoing problems due to nerve damage.
If you have been diagnosed with pernicious anemia, you should tell your family members about the disease – especially your children and your siblings. Because pernicious anemia runs in families, they may be more likely to develop the disease.