Ovulation induction increases serum levels of insulin-like growth factor binding protein 1

The effect of ovulation induction on serum insulin-like growth factor binding protein 1 (IGFBP-1) level in relation to sex hormone binding globulin (SHBG) levels was evaluated. Serum samples were collected 8 to 12 days after ovulation from 26 women undergoing ovulation induction with clomiphene citrate (CC), and from 58 women treated with CC in combination with human menopausal gonadotropin (hMG) and human chorionic gonadotropin (hCG). In addition, serum samples were obtained from 63 spontaneously ovulating women and from 12 women during an anovulatory cycle. Luteal phase serum IGFBP-1 levels were 4.22 +/- 2.95 micrograms/L (P less than .05) in the CC group and 7.31 +/- 6.13 micrograms/L (P less than .001) in the CC/hMG/hCG group as compared to unstimulated ovulatory cycles (2.64 +/- 2.52 micrograms/L). No significant difference in IGFBP-1 levels was seen between spontaneously ovulatory and anovulatory cycles. The serum IGFBP-1 levels correlated positively to SHBG levels (r = .52, P less than .001). The data show that ovulation induction increases serum IGFBP-1 levels in parallel to SHBG levels, indicating that ovarian stimulation, which results in increased steroid hormone production, also induces changes in other factors known to modulate steroid hormone actions.