Physiological Intravascular Hemolysis of Exercise. Hemoglobinemia and Hemoglobinuria following Cross-country Runs.

Studies on 3 cases of march hemoglobinuria were recently reported from this laboratory and the existing literature concerning this syndrome was reviewed (1). In 1 patient of our series and in some other reported instances, frank hemoglobinuria has been observed following walks of only 20 minutes' duration. Such occurrences are obviously unusual and are considered to be due to some as yet unrecognized and apparently benign abnormality (1). There are, however, other reported cases in which hemoglobinuria occurred only after very long, strenuous walks or after long runs. The question arises whether intravascular hemolysis, giving rise to hemoglobinemia and sometimes hemoglobinuria, occurs with sufficient frequency in certain types of strenuous exercise of long duration to be considered physiological. To gain information in this regard, a study was made of the incidence and degree of intravascular hemolysis in normal individuals performing long strenuous runs; the results of these studies and of other urinary and blood studies pertinent to the problem are reported and discussed herein.