Cyclic changes in endometrial tissue plasminogen activator and plasminogen activator inhibitor type 1 in women with normal menstruation and essential menorrhagia.

OBJECTIVE

The purpose of this study was to investigate the role of fibrinolysis in the pathogenesis of essential menorrhagia.

STUDY DESIGN

We measured fibrinolytic activity and the concentration of the fibrinolytic activators, tissue plasminogen activator, and plasminogen activator inhibitor type 1 in endometrial extracts at various stages of the menstrual cycle in patients with normal menstrual loss (< or = 80 ml per cycle) and essential menorrhagia (> 80 ml per cycle). Tissue plasminogen activator activity was assayed by measuring the rate of conversion of Glu-plasminogen to plasmin with a chromogenic plasmin substrate. Enzyme-linked immunoassays were used to measure tissue plasminogen activator and plasminogen activator inhibitor type 1 antigen levels.

RESULTS

Women with essential menorrhagia had higher endometrial tissue plasminogen activator activity in the menstrual phase compared with controls (p < 0.01). Endometrial tissue plasminogen activator antigen levels were higher in both the late secretory (p < 0.01) and menstrual (p < 0.001) phases in essential menorrhagia than in the normal group. Endometrial plasminogen activator inhibitor type 1 was significantly higher in essential menorrhagia only in the menstrual phase (p < 0.01).

CONCLUSION

The premenstrual rise in tissue plasminogen activator antigen production with delayed increase in plasminogen activator inhibitor type 1 is the probable cause of the greater endometrial tissue plasminogen activator activity that occurs during menstruation in women with essential menorrhagia.