Pernicious anemia: Description, Causes and Risk Factors:ICD-10: D51.0.Abbreviation: PA.Alternative Names: Biermer anemia, addisonian anemia, macrocytic achylic anemia, Biermer disease, malignant anemia, Addison anemia, Addison-Biermer disease.In the classical definition, PA refers only to vitamin B12 deficiency anemia caused by a lack of intrinsic factor (IF).Vitamin B12 is very essential for:
Production of red blood cells (RBCs).
Growth and development of children.
Maintenance of the nervous system.
Pernicious anemia is the most common cause of vitamin B12 deficiency. Vitamin B12 deficiency has many causes; the term “pernicious anemia” applies only to the condition associated with chronic atrophic gastritis (CAG).There are three regions of the stomach: the fundus and the body, both of which contain acid secreting gastric parietal cells and pepsinogen secreting zymogenic cells, and the antrum, which contains gastrin-producing cells.Chronic atrophic gastritis is recognized macroscopically by the loss of gastric mucosal folds and thinning of the gastric mucosa. It can be classified into two types according to whether or not the lesion affects the gastric antrum Type A (autoimmune) gastritis involves the fundus and body of the stomach and spares the antrum, whereas type B (nonautoimmune) gastritis involves the antrum as well as the fundus and body. Type A gastritis is associated with pernicious anemia, autoantibodies to gastric parietal cells and to intrinsic factor, achlorhydria, low serum pepsinogen I concentrations, and high serum gastrin concentrations, the latter resulting from hyperplasia of gastrin-producing cells. Type B gastritis is usually associated with Helicobacter pylori infection and low serum gastrin concentrations, because of destruction of the gastrin-producing cells associated with antral gastritis.Pernicious anemia is the end stage of type A chronic atrophic (autoimmune) gastritis. The gastritis results in the loss of parietal cells in the fundus and body of the stomach. The loss of these cells is associated with the failure of intrinsic-factor production and results in vitamin B12 deficiency. An autoimmune basis for the gastritis is supported by the presence of mononuclear-cell infiltration into the gastric mucosa with loss of parietal and zymogenic cells, autoantibodies to parietal cells and intrinsic factor.There is a rare congenital form of pernicious anemia in which babies are born lacking the ability to produce effective intrinsic factor. There is also a juvenile form of the disease, but pernicious anemia typically does not appear before the age of 30.Risk Factors May Include:
Age over 40.
Stomach surgery, stomach cancer, or gastritis.
Diabetes and autoimmune disorders.
Myxedema, Graves' disease, or other thyroid disorders.
Genetic factors, such as in people of Northern European ancestry. It is rare in blacks and Asians.
Family history of pernicious anemia.
Strict vegetarian diet or infants breast-fed by a mother on a strict vegetarian diet.
Lack of stomach acid in older adults.
Parasitic infections and intestinal diseases.
Some drugs such as H2 blockers, proton pump inhibitors, colchicine, neomycin, and aminosalicylic acid.
Diagnosis:A detailed clinical history, physical exam, and laboratory investigations are sufficient to diagnose the presence of pernicious anemia.Laboratory tests and clinical exams together reveal the severity of the disease and the appropriate mode of treatment. More often, anemia is an incidental finding and the deficiency itself causes no symptoms in the patient. In fact, it is often unexpectedly discovered in a routine check-up. Tests that may used to diagnose or monitor pernicious anemia include:
Complete blood count.
Measurement of serum holotranscobalamin II.
Serum methylmalonic acid (MMA) level.
Serum vitamin B12 level.
A Schilling test will confirm that the vitamin B12deficiency is the result of intestinal malabsorptiondue to intrinsic-factor deficiency. In patients withpernicious anemia, urinary excretion of orally administered vitamin B12is low, and it increases if vitamin B12is administered with intrinsic factor. Asimpler test is measurement of serum holotranscobalamin II, the circulating protein that delivers vitamin B12to cells. In patients with vitamin B12deficiency, serum concentrations of holotranscobalaminII fall before those of vitamin B12.Treatment:As pernicious anemia is a form of vitamin B12 deficiency, the treatment of choice is to provide adequate vitamin B12 through supplements. This is done either by injections of vitamin B12 or oral supplements of vitamin B12 daily.Monthly vitamin B12 injections are prescribed to correct the vitamin B12 deficiency. This therapy treats the anemia and may correct the neurological complications if taken early enough. In people with a severe deficiency, the injections are given more frequently at first.Some doctors recommend that elderly patients with gastric atrophy take vitamin B12 supplements by mouth in addition to monthly injections.There is also a preparation of vitamin B12 that may be given through the nose. For some people, taking vitamin B12 by mouth in a very high dose can also be an effective treatment.A well-balanced diet is essential to provide other elements for healthy blood cell development, such as folic acid, iron, and vitamin C.NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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