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 factor-I (IGF-I), IGF binding protein- 1 (IGFBP- 1) and IGFBP-3 levels in menstrual cycles treated with or without antiestrogens (clomiphene citrate and tamoxifen), 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 antiestrogens, 12 women with regular menstrual cycles were recruited as controls. There was a preovulatory (day 13) peak of circulating IGFBP-1 in women treated with or without antiestrogens. A signifcant concomitant increase in serum estradiol was also observed on day 13 of the menstrual cycle in subjects treated with domiphene citrate and in controls. However, no signifcant elevation in preovulatory estradiol was detected in women treated with tamoxifen. In domiphene citrate and control groups, a signifcant positive correlation was found between circulating IGFBP-1 and estradiol, and between serum 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. Unlike cydic changes in circulating IGFBP-1, serum concentrations of IGF-I and IGFBP-3 remained unchanged throughout the menstrual cycle in all groups. In conclusion, the preovulatory peak of circulating IGFBP-1 can be induced in cycles treated with both domiphene citrate and tamoxifen. In addition, a significant positive correlation between estradiol, inhibin A and IGFBP-1 at the preovulatory stage indicates that IGFBP-1 may also reflect follicular development and may further be used as an additional indicator to monitor folliculogenesis under domiphene citrate treatment.