The Schilling test distinguished PA from other forms of B12 deficiency, specifically, from Imerslund–Gräsbeck syndrome, a B12-deficiency caused by mutations in CUBN that codes for cubilin the cobalamin receptor. Treatment
Pernicious anemia may not be diagnosed at first. More in-depth diagnosis may be required. Pernicious anemia caused by a loss of intrinsic factor cannot be prevented. If there are other, reversible causes of low vitamin B12 levels, the cause must be treated. Pernicious anemia is usually easily treated by providing the necessary level of vitamin B12 supplementation. Severe cases can be treated with intramuscular injections of vitamin B12. Less severe cases may be treated with high doses of oral supplemenation of vitamin B12. A nasal spray, gel, and sublingual preparation are also available for people who may have difficulty in swallowing. Folate supplementation may affect the course and treatment of pernicious anemia, therefore vitamin B12 replacement is often recommended initially. In some severe cases of anemia, a blood transfusion may be needed to resolves haematological effects. Often treatment will be needed for life. Prognosis
A person with well-treated PA can live a healthy life. Failure to diagnose and treat in time, however, may result in permanent neurological damage, excessive fatigue, depression, memory loss, and other complications. In severe cases, the neurological complications of pernicious anemia can lead to death – hence the name, "pernicious", meaning deadly.There is an increased risk of gastric cancer in those with pernicious anemia linked to the common feature of atrophic gastritis.
Pernicious anemia can contribute to a delay in physical growth in children, and may also be a cause for delay in puberty for adolescents. Causes
Vitamin B12 cannot be produced by the human body, and must be obtained from the diet. When foods containing B12 are eaten, the vitamin is usually bound to protein and is released by proteases released by the pancreas into the small bowel. Following its release, most B12 is absorbed by the body in the small bowel (ileum) after binding to a protein known as intrinsic factor. Intrinsic factor is produced by parietal cells of the gastric mucosa (stomach lining) and the intrinsic factor-B12-complex is absorbed by enterocytes in the ileums cubam receptors. PA is characterised by B12 deficiency caused by the absence of intrinsic factor. Other disorders that can disrupt the absorption of vitamin B12 in the small intestine include celiac disease, surgical removal of crohns disease, and HIV. PA may be considered as an end stage of autoimmune atrophic gastritis, a disease characterised by stomach atrophy and the presence of antibodies to parietal cells and intrinsic factor. Autoimmune atrophic gastritis, is localised to the body of the stomach, where parietal cells are located. Antibodies to intrinsic factor and parietal cells cause the destruction of the oxyntic gastric mucosa, in which the parietal cells are located, leading to the subsequent loss of intrinsic factor synthesis. Without intrinsic factor, the ileum can no longer absorb the B12.