While the precipitating cause of march hemoglobinuria is implicit in the name, its etiology has so far eluded full understanding. Many theories came and went since Fleischer first described this condition 86 years ago. Red cell abnormalities, circulating antibodies, faulty renal mechanisms, and postural and other factors have been suspected at various times but have subsequently been cleared for lack of evidence. Erythrocyte fragility has been consistently normal, the Coombs' test negative, and renal function unimpaired. Even exercise—so essential, it seemed, that the disorder was often referred to as "exertional hemoglobinuria"—is no longer considered relevant, since neither swimming nor cycling nor any other strenuous activity would duplicate the hemoglobinuric effect of marching.
Superficial trauma rather than effort emerges as the trigger. Marching on soft surfaces or wearing shoes with foam rubber insoles forestalls the hemolytic process. It is thought that mechanical damage to red cells in the soles of the