Hemolysis in sickle cell disease as measured by endogenous carbon monoxide production. A preliminary report

To detect and quantitate temporal variations of the hemolytic rate in sickle cell disease, the authors measured endogenous carbon monoxide (CO) production in five normal subjects, nine patients with sickle cell anemia (SS) in steady clinical state, and two patients with sickle cell-hemoglobin C (SC) disease in and out of pain crises. The red blood cell life span calculated from these data (RCLSco) ranged from 81.2 to 102.9 days (mean +/- standard deviation [SD] 88.0 +/- 9.2, coefficient of variation [CV] 10.2%) for the normal subjects and 8.0-24.7 days (mean +/- SD 12.1 +/- 5.1, CV 42.1%) for those with SS. Although the individual figures for RCLSco for the normal subjects and those with SS fell within the range previously obtained by radioisotopic techniques for the respective groups, the mean values calculated from the CO technique were slightly (though not significantly) shorter for the normal subjects and about 25% shorter for the subjects with SS (P less than 0.01). Repetitive studies were performed in four subjects with SS who were clinically stable; the temporal variability in the calculated hemolytic rate differed considerably from patient to patient (CV 3.6%, 7.0%, 17.0%, 28.0%). In two patients concurrent RCLS studies were performed by the CO technique and 51Cr tagged red blood cells. In one patient, the RCLS was similar by the two techniques, in the other, a two exponent 51Cr curve did not permit calculation of RCLS. In the two patients with SC disease there was no difference in RCLSco during and after recovery from pain crisis. Although the CO technique may overestimate the turnover of circulating heme mass, especially in the presence of hemolysis, the results of serial studies in a small number of patients with SS suggest but do not prove temporal variations in hemolytic rate in SS.