Cyclic changes in serum levels of insulin-like growth factor binding protein-1 in women treated with clomiphene citrate and tamoxifen

In order to investigate the cyclic changes of serum insulin-like growth fac tor-I (IGF-I), IGF binding protein-1 (IGFBP-1) and IGFBP-3 levels in menstr ual cycles treated with or without antiestrogens (clomiphene citrate and ta moxifen), we treated 24 young women having irregular menstrual cycles with either clomiphene citrate (100 mg/day) (n = 12) or tamoxifen (60 mg/day) (n = 12) from the 5th to the 9th day of the menstrual cycle. Without antiestr ogens, 12 women with regular menstrual cycles were recruited as controls. T here was a preovulatory (day 13) peak of circulating IGFBP-1 in women treat ed with or without antiestrogens. A significant concomitant increase in ser um estradiol was also observed on day 23 of the menstrual cycle in subjects treated with clomiphene citrate and in controls. However, no significant e valuation in preovulatory estradiol was detected in women treated with tamo xifen. In clomiphene citrate and control groups, a significant positive cor relation was found between circulating IGFBP-1 and estradiol, and between s erum levels of IGFBP-1 and inhibin A at the preovulatory stage (on day 13). In contrast, no such association was observed in the tamoxifen group. Unli ke cyclic changes in circulating IGFBP-1, serum concentrations of IGF-I and IGFBP-3 remained unchanged throughout the menstrual cycle in all groups. I n conclusion, the preovulatory peak of circulating ICFBP-1 can be induced i n cycles treated with both clomiphene citrate and tamoxifen. In addition, a significant positive correlation between estradiol, inhibin A and ICFBP-1 at the preovulatory stage indicates that ICFBP-1 may also reflect follicula r development and may further be used as an additional indicator to monitor folliculogenesis under clomiphene citrate treatment.