Soon after the start of the parenteral infusion of the 57FeSO4 solution, the enteral 58FeSO4 will be given to the children. During this time, parenteral infusion of 57FeSO4 will be continued. After checking to ensure that the nasogastric feeding tube is properly located in the stomach, the tube will be aspirated to check stomach contents. If the stomach is empty, 1.5 ml of the 58 FeSO4 will be delivered directly via a syringe into the feeding tube. The tube will then be flushed with 0.5 ml of sterile water. The dosage of parenteral 57FeSO4 will be 0.15mg/kg (57Fe-enriched ferrous sulfate solution), which would provide 0.12 mg/kg of 57Fe. The dosage of enteral will be 1.5mg/kg (58Fe-enriched ferrous sulfate solution), which will provide 0.8mg/kg of 58Fe. The children will be discharged with therapy for Helicobacter pylori infection (Klarithromycin plus omeprazole) for 10 days.