Pernicious Anemia

Pernicious anemia is a chronic illness caused by less or no absorption of vitamin B-12 because of a lack of an intrinsic factor (IF) in the gastric secretions. Pernicious anemia may occur as a relatively common adult form of anemia that is associated with gastric atrophy and a loss of IF production It may also occur as a rare congenital autosomal recessive form in which IF production is lacking without gastric atrophy. The disease was called pernicious anemia as it was fatal until treatment was found in the form of liver therapy and later as purified vitamin B-12.

Pernicious Anemia

While the term pernicious anemia is mostly used for patients with vitamin B-12 deficiency due to a lack of production of IF in the stomach, vitamin B-12 absorption is complex and other causes of vitamin B-12 deficiency exist. When gastric parietal cells fail to produce sufficient IF, enough to allow the absorption of dietary vitamin B-12, it causes classic pernicious anemia.

Other disorders that interfere with the absorption and metabolism of vitamin B-12 can produce cobalamin deficiency. Dietary cobalamin is acquired mostly from meat and milk and is absorbed in a series of steps, which require release from foodstuffs and binding to a gastric protein cells that is known as IF. Likewise, binding and blocking antibodies to IF is seen in most patients suffering from pernicious anemia. An association that is greater than anticipated exists between pernicious anemia and other autoimmune diseases, which include thyroid disorders, type I diabetes mellitus, ulcerative colitis, Addison disease, infertility, and acquired agammaglobulinemia.

Cobalamin deficiency, which is the main cause of pernicious anemia, may result from dietary insufficiency of vitamin B-12, disorders of the stomach, small bowel, and pancreas, certain infections, and abnormalities of transport, metabolism, and utilization . Abnormalities in the intestines may produce cobalamin deficiency. Individuals with blind intestinal loops, stricture, and large diverticula may develop bacterial overgrowth, which sequesters dietary Cobalamin for their metabolic needs. Tapeworm infestation with Diphyllobothrium latum occurs from eating poorly cooked lake fish that are infected and causes cobalamin deficiency because the parasites have a high requirement for cobalamin.

The onset of pernicious anemia is usually insidious and vague and the classic triad of weakness, sore tongue, and paresthesias may be seen but is not the chief symptom complex. The patient suffering from pernicious anemia generally seek medical attention, after discovering symptoms related to cardiac, renal, genitourinary, gastrointestinal, infectious, mental, or neurological disorders. Weight loss of 10-15 pounds occurs in about 50% of patients and probably is due to anorexia, which is observed in most patients. Low-grade fever occurs in approx 30% of the newly diagnosed patients and usually disappears soon with treatment. About half of the patients have a smooth tongue with loss of papillae, seen at the edges of the tongue. The tongue may be painful and beefy red. Patients complain of constipation or altered bowel habits. Nonspecific gastrointestinal symptoms are also manifested and include anorexia, nausea, vomiting, heartburn, pyrosis, flatulence, and a sense of fullness. In Pernicious anemia, neurological symptoms can be in the form of paresthesias, weakness, clumsiness, and an unsteady gait.