TAILIEUCHUNG - Chapter 100. Megaloblastic Anemias (Part 12)

Nutritional Dietary folate deficiency is common. Indeed, in most patients with folate deficiency a nutritional element is present. Certain individuals are particularly prone to have diets containing inadequate amounts of folate (Table 100-5). In the United States and other countries where fortification of the diet with folic acid has been adopted, the prevalence of folate deficiency has dropped dramatically and is now almost restricted to high-risk groups with increased folate needs. Nutritional folate deficiency occurs in kwashiorkor and scurvy and in infants with repeated infections or who are fed solely on goats' milk, which has a low folate content. Malabsorption Malabsorption. | Chapter 100. Megaloblastic Anemias Part 12 Nutritional Dietary folate deficiency is common. Indeed in most patients with folate deficiency a nutritional element is present. Certain individuals are particularly prone to have diets containing inadequate amounts of folate Table 100-5 . In the United States and other countries where fortification of the diet with folic acid has been adopted the prevalence of folate deficiency has dropped dramatically and is now almost restricted to high-risk groups with increased folate needs. Nutritional folate deficiency occurs in kwashiorkor and scurvy and in infants with repeated infections or who are fed solely on goats milk which has a low folate content. Malabsorption Malabsorption of dietary folate occurs in tropical sprue and in gluten-induced enteropathy. In the rare congenital syndrome of selective malabsorption of folate there is an associated defect of folate transport into the cerebrospinal fluid and these patients show megaloblastic anemia which responds to physiologic doses of folic acid given parenterally but not orally. They also show mental retardation convulsions and other central nervous system abnormalities. Minor degrees of malabsorption may also occur following jejunal resection or partial gastrectomy in Crohn s disease and in systemic infections but in these conditions if severe deficiency occurs it is usually largely due to poor nutrition. Malabsorption of folate has been described in patients receiving salazopyrine cholestyramine and triamterene. Excess Utilization or Loss Pregnancy Folate requirements are increased by 200-300 pg to 400 pg daily in a normal pregnancy partly because of transfer of the vitamin to the fetus but mainly because of increased folate catabolism due to cleavage of folate coenzymes in rapidly proliferating tissues. Megaloblastic anemia due to this deficiency is prevented by prophylactic folic acid therapy. It occurred in of pregnancies in the UK and other Western countries before .

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