[Lienal and intravascular corpuscular hemolysis in erythropoietic protoporphyria]

A report is presented on two brothers with erythropoietic protoporphyria (EPP) with massively and moderately elevated RBC-protoporphyrin content respectively. Both exhibited splenic and one also intravascular hemolysis. The mechanism of hemolysis was investigated on the basis of filterability, plasma trapping and osmotic resistance of in vivo RBCs and of incubated, UV-light exposed RBCs. Photodynamic damage to EPP-RBC, leading to increased RBC rigidity, increased splenic trapping and intravascular hemolysis, appears to play a crucial role in the causation of hemolysis in vivo as well as in vitro.