1. To investigate the age-related changes in factor VII activation in healthy women, a regular factor VII clotting assay (factor VIIc) was carried out simultaneously with a new enzyme immunoassay for the quantification of antigen factor VII (factor VIIag).
2. Both factor VIIc and factor VIIag levels were positively correlated with age (r = 0.79 and r = 0.62, respectively, n = 25, P < 0.001). The rise with age in factor VIIc was steeper than in factor VIlag and the ratio of factor VIIc to factor VIlag (an indicator of the activity state of factor VII) increased with age (r = 0.42, P < 0.05).
3. The results show that an increased conversion of native single-chain factor VII to the fully active double-chain form is associated with advancing age in women.
4. This finding is consistent with a possible role of activated factor VII in the pathogenesis of thromboocclusive vascular disease in women.