[The fate of hemoglobin in the plasma]

The following aspects of intravascular hemolysis are briefly reviewed: pathogenesis; binding of hemoglobin to haptoglobin, hemopexin or serum albumin; hemoglobin oxidation, dissociation and renal excretion. The dissociation constant of hemoglobin tetramer into dimers was determined by gel filtration at 37 degrees C, using normal plasma for elution. This constant (5.1 x 10(-6) mol/l was used for calculation of renal clearance of hemoglobin. The rate of hemoglobin autooxidation was measured in normal plasma applying varying partial oxygen pressures. The results confirm that the formation of methemoglobin is enhanced under hypoxic conditions.