Urinary iron excretion and renal metabolism of hemoglobin in hemolytic diseases.

IT HAS BEEN KNOWN for many years that hemosiderin can be identified in the urinary sediment of patients with intravascular hemolysis,”2 and significant urinary losses of nonhemoglobin iron have been shown to occur in cases of paroxysmal nocturnal hemoglobinunia3 and sickle cell anemia.4 Since nonhemoglobin iron compounds appearing in the urine of patients with intravascular hemolysis presumably are products of renal tubular metabolism of filtered hemoglobin, quantitative and qualitative studies of the urinary iron in such patients should provide information about the nature and capacity of tubular hemoglobin metabolism and its significance in hemolytic disease. The present study was undertaken ( 1 ) to quantify urinary iron in patients with various hemolytic diseases, particularly those in which intravascular hemolysis is prominent, ( 2 ) to ascertain the location of iron in different fnactions of the urine, (3) to identify fernitin in the urine as one of the products of renal tubular metabolism of hemoglobiim, ( 4 ) to compare diurnal patterns of hemolysis and iron excretion, ( 5 ) to relate the findings to current concepts of renal clearance and metabolism of hemoglobin, and (6) to assess the impontance of this aveimue of iron loss in body iron balance. In addition to the study of patients, urinary iron and hemoglobin excretion were evaluated in a normal subject given an infusion of hemoglobin.