Activin A is a growth factor, produced by the endometrium, whose actions are modulated by the binding protein follistatin. Both proteins are detectable in the peripheral serum and their concentrations may be increased in women with endometriosis. The present study was designed to evaluate whether serum levels of activin A and follistatin are altered, and therefore have a potential diagnostic value, in women with peritoneal, ovarian and deep infiltrating endometriosis.
We performed a multicenter controlled study evaluating simultaneously serum activin A and follistatin concentrations in women with and without endometriosis. Women with endometriosis (n = 139) were subdivided into three groups: peritoneal endometriosis (n = 28); ovarian endometrioma (n = 61) and deep infiltrating endometriosis (n = 50). The control group (n = 75) consisted of healthy women with regular menstrual cycles. Blood samples were collected from a peripheral vein and assayed for activin A and follistatin using commercially available enzyme immunoassay kits.
The ovarian endometrioma group had serum activin A levels significantly higher than healthy controls (0.22 ± 0.01 ng/ml versus 0.17 ± 0.01 ng/ml, P < 0.01). None of the endometriosis groups had serum follistatin levels which were significantly altered compared with healthy controls; however, levels found in the endometrioma group (2.34 ± 0.32 ng/ml) were higher than that in the deep endometriosis group (1.50 ± 0.17 ng/ml, P < 0.05). The area under the receiver operating characteristic curve of activin A was 0.700 (95% confidence interval: 0.605-0.794), while that of follistatin was 0.620 (95% confidence interval: 0.510-0.730) for the diagnosis of ovarian endometrioma. The combination of both markers into a duo marker index did not improve significantly their diagnostic accuracy.
The present study demonstrated that serum activin A and follistatin are not significantly altered in peritoneal or deep infiltrating endometriosis and have limited diagnostic accuracy in the diagnosis of ovarian endometrioma.