Defective release of tissue plasminogen activator in patients with sickle cell anemia.

Recent studies suggest that intravascular coagulation occurs in sickle cell anemia. There is also some evidence that decreased fibrinolytic activity may be associated with the disorder. In the current study we measured tissue plasminogen activator levels (t-PA) in seven asymptomatic patients with sickle cell anemia. The mean level of releasable t-PA was only 0.01 IU/mL +/- 0.005 (SEM) as compared to 118 healthy volunteers with levels of 0.70 +/- 0.10 (SEM). Despite the small sample size, the difference between the two groups was statistically significant (P less than .001). These data suggest that defective release of t-PA may contribute to a hypercoagulable state in sickle cell anemia.