Methods Follistatin, follicle-stimulating hormone (FSH), estradiol (E₂) were studied in serum of 42 adolescent girls aged 15–17 years with different clinical symptoms of HA (acne, hirsutism) and irregular menstrual cycle (IMC), 42 patients with regularmenstrual cycle (RMC) and 30 healthy adolescents.

Results Hyperandrogenic patients with IMC showed an increased follistatin secretion (p? =0,03) compared to a group with RMC and control group. This fact points to the involvement of this glycoprotein in the pathogenesis of ovarian dysfunctionin girls’ puberty. Also we found significant negative correlation between the levels of FSH and follistatin (p = 0,02) that proved the inverse relationship between secretion of gonadotropins and follistatin level. Besides the negative correlation between follistatin and E₂ has been revealed (p = 0,04).

Conclusions It may be difficult to distinguish biologically and ultrasonically hyperandrogenic adolescents as the result of normalmaturational process of puberty from the ones with developing polycystic ovarian syndrome (PCOS). The increased secretion of follistatin and its correlation with the reduction of FSH and estradiol in adolescent girls with menstrual irregularities and hyperandrogenism confirms the pathological role of this intraovarian factor in discoordination of peripheral functioning of reproductive system, and its possible significance in pathogenesis of PCOS as a future outcome of pubertal hyperandrogenism.