Urinary iron excretion in thalassaemia after desferri-

oxamine administration. Urinary iron excretion induced with desferrioxamine (DFA) was estimated in 26 children with thalassaemia major. Four separate 24-hour urine collections were made-during a baseline period, after intramuscular injection of DFA 1 g, during blood transfusion with DFA 0 5 g/unit transfused blood, and during the post-transfusion period. Urinary iron, plasma iron, and total iron-binding capacity were estimated by atomic absorption spectrophotometry. Urinary iron excretion in the 24 hours after 1 g DFA ranged from 1 1 to 23 mg/M2 surface area compared with 0 * 1 to 1 * 6 mg/M2 during the baseline period. A positive correlation was obtained between DFA-induced urinary iron excretion and the amount of blood transfused, plasma iron level, and size of the spleen. Splenectomized patients excreted less iron after DFA than those who were not splenectomized. DFA-induced urinary iron was measured before and after splenectomy in 6 patients. In 5 of the 6 patients a drop in iron excretion was observed and the analysis of the 6 pairs of results indicated that splenectomy produced a decrease in DFA-induced urinary iron excretion. These findings indicate that the enlarged spleen in thalassaemia is a major source of iron chelated by DFA. It is suggested that treatment with DFA in the presence of a large spleen may be ineffective in removing excess iron from the myocardium and liver.