Quantitative and qualitative studies of urinary iron excretion were performed in 12 patients with hemolytic disease and in one normal subject given an intravenous infusion of hemoglobin. In 9 patients with significant intravascular hemolysis, increased urinary excretion of nonhemoglobin iron was observed with amounts as high as 10.75 mg. pen 24 hours. In 7 of 8 patients in whom fractions of the urinary iron were studied, the majority of the iron was in the sediment (hemosiderin). Ferritin was demonstrated in the urine by immunologic and electrophoretic technics and accounted for a significant percentage of iron excreted. In several patients, day-night variations in hemolysis were associated with parallel fluctuations in iron excretion.
The results were analyzed in relation to current concepts of glomerular clearance and renal tubular metabolism of hemoglobin. The significance to body iron balance of the massive "iron diuresis" occurring in some of these patients was discussed.