Study of platelet function in patients with sickle cell anemia during steady state and vaso-occlusive crisis.

Although there are many reports providing evidence for platelet hyperactivity during acute infarctive crisis in sickle cell disease, little attention has been paid to the study of platelet release reaction in steady state. Plasma levels of the alpha-granule constituents beta-thromboglobulin and platelet factor 4 were measured in patients with sickle cell anemia during steady state and vaso-occlusive crisis in order to determine in vivo platelet activity. Significantly higher plasma levels of both proteins were found in steady state and in crisis when compared with those of normal controls. Platelet hyperactivity was also found to be more vigorous in painful crisis, suggesting a possible therapeutic role for drugs that inhibit platelet function.