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.