Hemolytic anemias glucose-6-phosphate dehydrogenase

Pyruvate kinase deficiency is the second most common genetic deficiency that causes a hemolytic anemia (glucose 6-phosphate dehydrogenase, G6PDH, is the most common). Characteristics include ... 

Genetic deficiency of glucose-6-phosphate dehydrogenase, with consequent impairment of the generation of NADPH, is common in populations of Mediterranean and Afro-Caribbean origin. The defect is manifested as red cell hemolysis (hemolytic anemia) when susceptible individuals are subjected to oxidants, such as the an-timalarial primaquine, aspirin, or sulfonamides or when... 

The pentose phosphate pathway is operative in the RBC (it metabolizes about 5-10% of the total flux of glucose) and produces NADPH hemolytic anemia due to a deficiency of the activity of glucose-6-phosphate dehydrogenase is common. 

It is an important intracellular reductant, helping to maintain essential SH groups of enzymes in their reduced state. This role is discussed in Chapter 20, and its involvement in the hemolytic anemia caused by deficiency of glucose-6-phosphate dehydrogenase is discussed in Ghapters 20 and 52. 

Glucose-6-phosphate dehydrogenase (G6PD) [mutations] (MIM 305900) Hemolytic anemia following ingestion of drugs such as primaquine... 

H9. Hirono, A., Fujii, H., Hirono, K., Kanno, H., and Miwa, S Molecular abnormality of a Japanese glucose-6-phosphate dehydrogenase variant (G6PD Tokyo) associated with hereditary non-spherocytic hemolytic anemia. Hum. Genet. 88,387-388 (1991). 

V14. Vulliamy, T. J D Urso, M., Battistuzzi, G Estrada, M., Foulkes, N. S., Martini, G., Calabro, V., Poggi, V., Giordano, R., Town, M., Luzzatto, L., and Persico, M. G Diverse point mutations in the human glucose-6-phosphate dehydrogenase gene cause enzyme deficiency and mild or severe hemolytic anemia. Proc. Natl. Acad. Sci. U.S.A. 85, 5171-5175 (1988). 

The answers are 484-k 485-j. (tlardman, pp 1061-1062, 1682-1685.) Sulfonamides can cause acute hemolytic anemia. In some patients it mayr be related to a sensitization phenomenon, and in other patients the hemolysis is due to a glucose-6-phosphate dehydrogenase deficiency Sulfamethoxazole alone or in combination with trimethoprim is used to treat UTls. The sulfonamide sulfasalazine is employed in the treatment of ulcerative colitis. Daps one, a drug that is used in the treatment of leprosy, and primaquine, an anti mala rial agent, can produce hemolysis, particularly in patients with a glucose-6-phosphate dehydrogenase deficiency. 

Hemolytic anemia results from decreased RBC survival time due to destruction in the spleen or circulation. The most common etiologies are RBC membrane defects (e.g., hereditary spherocytosis), altered Hb solubility or stability (e.g., sickle cell anemia [see Chap. 34] and thalassemias), and changes in intracellular metabolism (e.g., glucose-6-phosphate dehydrogenase deficiency). Some drugs cause direct oxidative damage to RBCs (see Appendix 3). 

Treatment of hemolytic anemia should focus on correcting the underlying cause. There is no specific therapy for glucose-6-phosphate dehydrogenase deficiency, so treatment consists of avoiding oxidant medications and chemicals. Steroids, other immunosuppressants, and even splenectomy can be indicated to reduce RBC destruction. 

Anthraquinone glycosides found in senna (Cassia fistulosa) and Aloe spp. have been included in some commercial cathartics. Vicine is a glycoside in fava beans (Vida faba), and causes hemolytic anemia in people who have a genetic deficiency of glucose-6-phosphate dehydrogenase activity in their red blood cells. Fava beans are grown as a protein supplement for livestock. 

In a fatal human exposure, a worker engaged in emptying metal gas cylinders of methyl mercaptan was found comatose at the work site he developed expiratory wheezes, elevated blood pressure, tachycardia, and marked rigidity of extremities. Methemoglobinemia and severe hemolytic anemia developed with hematuria and proteinuria but were brief in duration deep coma persisted until death due to pulmonary embolus 28 days after exposure. It was determined that the individual was deficient in erythrocyte glucose-6-phosphate dehydrogenase, which was the likely cause of the hemolysis and formation of methemoglobin. 

Ulcerative colitis Inform patients with this condition that ulcerative colitis rarely remits completely, and that the risk of relapse can be substantially reduced by continued administration of sulfasalazine at a maintenance dosage. Glucose-6-phosphate dehydrogenase deficiency Observe patients with glucose-6-phosphate dehydrogenase deficiency closely for signs of hemolytic anemia. This reaction is frequently dose-related. 

The sulfones can produce nonhemolytic anemia, methemoglobinemia, and sometimes acute hemolytic anemia in persons with a glucose-6-phosphate dehydrogenase deficiency. Within a few weeks of therapy some... 

Sulfonamides can cause hemolytic or aplastic anemia, granulocytopenia, thrombocytopenia, or leukemoid reactions. Sulfonamides may provoke hemolytic reactions in patients with glucose-6-phosphate dehydrogenase deficiency. Sulfonamides taken near the end of pregnancy increase the risk of kernicterus in newborns. 

Anorexia, nausea, and vomiting are the principal side effects of nitrofurantoin. Neuropathies and hemolytic anemia occur in glucose-6-phosphate dehydrogenase deficiency. Nitrofurantoin antagonizes the action of nalidixic acid. Rashes, pulmonary infiltration and fibrosis, and other hypersensitivity reactions have been reported. 

There are examples where several genetic factors, including the acetylator phenotype, operate together. Hydralazine toxicity is one such example, which is discussed in detail in chapter 7. Another is the hemolytic anemia caused by the drug thiozalsulfone (Promizole), which occurs particularly in those individuals who are both glucose-6-phosphate dehydrogenase deficient and slow acetylators. Promizole is acetylated, and studies in rapid and slow acetylator mice confirmed that acetylation was a factor as well as an extent of hydroxylation. The latter may also be another factor in humans as is discussed below. 

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