Intravascular hemolysis Intravascular hemolysis is an important reason for premature RBC destruction and occurs when the cell membrane has been severely damaged by any of a number of different mechanisms, including Autoimmune phenomena Direct trauma (eg, march hemoglobinuria) Shear stress (eg, defective mechanical heart valves) Disseminated intravascular coagulation (DIC) Toxins (eg, clostridial toxins, venomous snake bite) Intravascular hemolysis results in hemoglobinemia when the amount of hemoglobin released into plasma exceeds the hemoglobin-binding capacity of the plasma-binding protein haptoglobin, a protein normally present in concentrations of about 100 mg / dL (1.0 g / L) in plasma.