Folic Acid Deficiency

Megaloblastic anemia resulting from folic acid deficiency secondary either to dietary deficiency or malabsorption syndrome. A genetically transmitted disorder with poor prognosis unless folinic acid is regularly administered.

Congenital Folate Malabsorption; Hereditary Folate Malabsorption; Transport Defect Involving Folic Acid.

Not well identified. Twelve cases of this rare disorder have been reported, mostly in females (but males can be affected).

Folic acid is reduced by dihydrofolate reductase to form tetrahydrofolate. Tetrahydrofolate is important in one carbon transfer reaction and essential in the methylation of deoxyuridylate to thymidylate during DNA synthesis. This leads to megaloblastic anemia, although the mechanism is poorly understood in nutritional diseases. Folic acid deficiency is caused by dietary deficiency, impaired absorption, or increased requirements. Nutritional deficiency is seen in the elderly, alcoholics, premature infants, infants raised on goat's milk and in hemodialysis, hyperalimentation, and gastrectomy patients. Impaired absorption occurs in sprue, regional enteritis, after extensive small bowel resections, in Whipple disease, and in leukemic infiltration of the intestine. Increased requirements are seen in pregnancy and in diseases with increased cell turnover, such as hemolytic anemia.

Clinical signs and symptoms are those of chronic anemia. Onset is insidious and associated with weakness, palpitation, fatigue, light-headedness, and dyspnea. Pallor and jaundice are common. Leukocyte and platelet counts may be depressed. Laboratory features include low serum and red cell folate, low reticulocyte count, macrocytic anemia, and hypersegmented neutrophils. Bone marrow examination reveals erythroid megaloblastic changes.

Hereditary form manifests as recurrent megaloblastic anemia, mental retardation, convulsions, movement disorder (ataxia), diarrhea, susceptibility to infections, and calcification of basal ganglia. Most patients die within the first few months of life as a consequence of diarrhea, vomiting, drowsiness, pallor, and glossitis.

Check hematocrit. Elective surgery is contraindicated until anemia resolves with treatment. In hereditary forms, avoid anesthesia unless there is a life-threatening surgical indication. Most infants are in very poor physical status with malnutrition and chronic dehydration. Check carefully fluid losses and avoid both underinflation and overinflation of fluids (intraoperatively and postoperatively). Provide IV folic acid and consider prophylactic antibiotics. Check acid balance status and plasma protein levels.

No specific anesthetic consideration with this condition except for potential severe anemia and epilepsy in the hereditary form. Transfuse with packed red blood cells as needed.

In hereditary form, reduce doses in patients with clinical and biologic signs of dehydration.

Dihydropteridine Reductase Deficiency: Same calcification of basal ganglia and same efficiency of folinic acid therapy.

Phenylketonuria Type II: Inborn error of phenylalanine metabolism. Results in severe irreversible mental retardation at thrive of infancy.