Pernicious anemia is a form of megaloblastic anemia that happens when a person's body is unable to absorb vitamin B12 from their gastrointestinal tract. Pernicious anemia is also known as, 'Congenital Pernicious Anemia,' 'Megaloblastic Anemia,' and, 'Combined Systems Disease.' Pernicious anemia involves a decrease in red blood cells due to the lack of absorption of vitamin B12, a nutrient which is required in order to develop these cells.
Pernicious anemia (also known as Biermer's anemia, Addison's anemia, or Addison-Biermer anemia) is one of many types of the larger family of megaloblastic anemias. One way pernicious anemia can develop is by loss of gastric parietal cells, which are responsible, in part, for the secretion of intrinsic factor, a protein essential for subsequent absorption of vitamin B12 in the ileum.
Persons with pernicious anemia are unable to absorb vitamin B12 from food because of a lack of, 'Intrinsic Factor,' a specific protein that is made in the stomach. There are also some additional conditions and factors that may cause a deficiency of vitamin B12. Examples of these include diet, medicines, infections, and surgery. People who pursue a strict vegetarian diet, or a poor diet, as well as older people and alcoholics may experience pernicious anemia.
People who have pernicious anemia have red blood cells that are too large and do not divide as they should. These red blood cells have trouble getting out of the person's bone marrow. Lacking sufficient numbers of red blood cells to carry oxygen to their body, the person may feel weak and tired. Pernicious anemia that is either long-lasting or severe can lead to damages to the person's brain, heart, or other organs in their body. Additional complications related to pernicious anemia can arise. Neurological problems including memory loss, the potential for nerve damage, as well as issues with the person's digestive tract can occur. Persons with pernicious anemia may also be at a higher risk for stomach cancer.
A lack of intrinsic factor is the cause of pernicious anemia. Intrinsic factor is a protein, produced in a person's stomach, which binds to vitamin B12. Common causes of pernicious anemia include a weakened stomach lining, autoimmunity against intrinsic factor, and the person's own immune system attacking the cells that make intrinsic factor. On rare occasion, an infant is born without the ability to produce intrinsic factor; when this occurs it is referred to as, 'Congenital Pernicious Anemia.' While congenital pernicious anemia does occur in children, adults commonly do not experience pernicious anemia prior to age thirty. The average age a person is diagnosed with pernicious anemia is age sixty.
Medical science does not understand why some people experience an autoimmune response that makes antibodies which attack and damage their body's cells or tissues. With pernicious anemia, the person's body produces antibodies that attack and destroy parietal cells in the lining of their stomach that create intrinsic factor. The result is that the person's body is unable to absorb vitamin B12, leading to a deficiency of the vitamin and pernicious anemia.
Removal of a portion of a person's stomach also reduces the number of parietal cells that create intrinsic factor, creating the potential for pernicious anemia. At times it occurs because a person's small intestine is unable to absorb vitamin B12; there may be too many of the wrong kinds of bacteria in their small intestine. These bacteria use the supply of vitamin B12 before the person can absorb it through their small intestine. There are some medications that can change the growth of bacteria, or prevent a person's small intestine from absorbing vitamin B12 as well. These medications are associated with treatment of seizure disorders or diabetes, as well as antibiotics. Crohn's disease and Celiac's disease may also interfere with the absorption of vitamin B12. Other causes of pernicious anemia can include a diet that is poor in vitamin B12, which can be received from foods such as poultry, meat, fish, dairy products, and eggs, as well as dietary supplements.
Strict vegetarians, as well as infants of mothers who are strict vegetarians who do not eat animal or dairy products and have been breastfed are at risk of pernicious anemia. People who are older, as well as alcoholics are at risk of pernicious anemia. Persons who have been infected with a tapeworm, as well as those who have eaten undercooked, infected fish can experience pernicious anemia.
In America, both women and men are at equal risk for developing the disease, although it it is most common among older adults and rare in children. Risk factors for pernicious anemia can include persons:
The symptoms of pernicious anemia are often related to those associated with a lack of vitamin B12 in the person's system. A lack of vitamin B12 can gradually cause nervous system issues that may present themselves prior to a diagnosis of pernicious anemia. Symptoms that can appear include:
A lack of vitamin B12 can lead to nerve damage that may present as numbness and tingling in the person's feet and hands, as well as a loss of their reflexes, or muscle weakness. The person may lose their balance, feel unsteady, or experience difficulty walking. Neurological issues, such as depression, confusion, memory loss or dementia may appear. A deficiency of vitamin B12 can lead to symptoms that involve the person's digestive tract as well. These symptoms include heartburn, nausea and vomiting, diarrhea, constipation, gas, bloating, weight loss, and loss of appetite. The person may experience and enlargement of their liver, or throat issues and a smooth, red tongue. Infants who are vitamin B12 deficient and do not receive treatment may experience permanent growth issues.
The low red blood cell count caused by pernicious anemia and a vitamin B12 deficiency can cause a person to experience dizziness, shortness of breath, cold feet or hands, and headache. They may also have pale nail beds, gums, and skin. A short supply of red blood cells requires the person's heart to work harder in order to circulate oxygen throughout their body, leading to the potential for chest pain and arrhythmias, heart enlargement, heart murmur, or potential heart failure.
A doctor attempts to diagnose pernicious anemia based upon the person's medical and family history, a physical examination, as well as results from various tests. One of the goals the doctor has is to find out if the condition is due to a lack of intrinsic factor, or if it is because of another cause. The doctor will also attempt to diagnose the severity of the condition and how best to treat it. Doctors that may become involved in attempts to diagnose pernicious anemia include a family doctor, pediatrician, neurologist, cardiologist, internist, gastroenterologist, or hematologist.
A doctor will ask about symptoms the person is experiencing, whether or not they have had any surgeries on their intestines or stomach, and whether or not they have any digestive disorders such as Crohn's disease. The doctor will ask the person if they have a family history of anemia or any autoimmune disorders. The doctor will also be interested in a list of the medications the person is taking and has taken over time, as well as the diet they eat.
The physical examination can involve checking for enlargement of the person's liver, listening to the person's heart for either a murmur or a rapid heartbeat, as well as checking for either yellowish or pale skin. The doctor might check for damage to the person's nerves, as well as to find out how well their muscles, senses, eyes, and reflexes are doing. The doctor could ask questions designed to check the person's mental well-being, and check their coordination and additional physical abilities.
There are a number of lab tests that can be used to either diagnose or monitor pernicious anemia. There are also lab tests that can be used to measure other things that are related to the disease which can help a doctor to treat persons with it. The tests that can be used by a doctor to either diagnose pernicious anemia, or to monitor it include:
Many times the first test a doctor will use in order to make a diagnosis of pernicious anemia is a Complete Blood Count test, which measures different parts of a person's blood. The test measures the amount of space that red blood cells are taking up in the person's blood, as well as the number of red blood cells, white blood cells, and platelets they have. Results outside of an average range for the person suggest anemia. The test also examines the size of the person's red blood cells; if the person's red blood cells are larger than average it is indicative of pernicious anemia.
Should the person present Complete Blood Count test results that are not within the average range, a doctor may order additional testing to discover what form of anemia they are experiencing. The Schilling test, for example, tests the person's urine to examine how well their body has absorbed vitamin B12 over time. Additional blood testing may include tests that look for:
Testing related to vitamin B12 levels can help a doctor to both treat and monitor persons with pernicious anemia. Folic acid an another form of B vitamin that can be tested for when a person's B12 level is low; a lack of folic acid may also cause anemia. The presence of a high level of Methylmalonic acid in persons with anemia is caused by a lack of vitamin B12 or folic acid and can be checked for through urine testing. Homocysteine levels are also increased in persons with anemia due to a lack of vitamin B12 or folic acid.
Should the need arise, a doctor can use bone marrow testing through either aspiration or a biopsy in order to determine if the person's bone marrow is healthy enough to produce a sufficient quantity of red blood cells. During a biopsy, a doctor uses a needle to remove a small amount of marrow. For a bone marrow aspiration, a doctor uses a needle to remove an amount of fluid bone marrow. Either sample is examined underneath a microscope for red blood cells that are larger than average, suggestive of pernicious anemia.
Pernicious anemia is referred to as, 'Pernicious,' due to the fact that is was many times fatal in the past. The development of vitamin B12 treatments became available, making pernicious anemia easily treatable through either shots or pills. Without treatment the disease can present serious problems that may become permanent, affecting a person's nerves, heart, as well as additional organs and other parts of their body. Persons with pernicious anemia who receive appropriate and ongoing treatment have the ability to not only recover, but to continue living their lives.
A monthly vitamin B12 injection can treat pernicious anemia; if the shots are given early enough they may even correct any neurological complications a person has experienced. For persons who are experiencing a severe deficiency these injections are administered at more frequent intervals to start. There are both oral and nasal preparations of vitamin B12 that can be administered as well. For older persons who experience gastric atrophy, a number of doctors recommend vitamin B12 supplements, taken orally, in addition to B12 monthly injections. A diet that is inclusive of iron, folic acid and vitamin C is also recommended. Many persons with pernicious anemia require lifelong treatment.
The goals of pernicious anemia treatment involve prevention and treatment of anemia, as well as its signs and symptoms. Treatment also involves either preventing or controlling any complications that may arise, such as nerve or heart damage. Attempts are made to treat the cause of pernicious anemia as well. A doctor may suggest that the person with pernicious anemia limit their activity until their symptoms related to the disease improve.
PA is estimated to affect 0.1% of the general population and 1.9% of those over 60, accounting for 20 to 50% of B12 deficiency in adults. It has been shown from a literature review that the prevalence of PA was higher in North European, especially for Scandinavian countries and African descent, in which high/increased awareness towards the disease and better diagnostic tools might partly play a role in it.