A 5-year-old boy is admitted to the pediatric ICU for severe iron overdose after ingesting a large quantity of his mother’s ferrous sulfate tablets. He initially presented with vomiting, diarrhea, abdominal pain, and metabolic acidosis. His serum iron level was 650 mcg/dL (normal: 50-150 mcg/dL). He was started on intravenous deferoxamine therapy, which has been continued for the past 30 hours. Over the past few hours, he has developed progressive respiratory distress, requiring increased oxygen support. Chest X-ray shows bilateral pulmonary infiltrates with no evidence of cardiomegaly or pleural effusions. Question: What is the most likely cause of this patient’s new-onset respiratory symptoms?
