Prior to iv administration to the children, 0.7-0.8 ml of the 57FeSO4 solution(0.2mg/ml) will be added to a burytrol containing 30 ml of the nutrient solution used for parenteral feeding, using sterile techniques. The iron-nutrient mixture, which has been used safely previously, will be infused slowly into a peripheral vein of the children over a 12-24 hour period with the aid of an infusion pump.