Erythrocyte deformability in sickle-cell crisis.

A serial study of erythrocyte deformability, plasma viscosity, and whole-blood viscosity has been made during 10 sickle-cell vaso-occlusive crises. The peak serum lactate dehydrogenase level was used to confirm the duration of crisis and the rheological changes were compared with 19 estimations made on the same patients when asymptomatic. Erythrocyte deformability, measured by filtration of washed erythrocytes through polycarbonate filters of 5 microgram pore size, was significantly reduced on day 1 of crisis and, in one additional patient, this occurred 24 h before the onset of pain. There was no increase in irreversibly-sick-led-cell counts and plasma- and blood-viscosity did not increase significantly until day 5 of crisis, in parallel with the acute-phase rise in plasma fibrinogen. Measurement of erythrocyte filterability is therefore a valuable technique for investigating the pathogenesis of the early stages of sickle-cell crisis.