Circulating levels of insulin-like growth factor binding protein 3 (IGFBP-3) and insulin-like growth factor I (IGF-I) in perimenopausal women.

The study investigated possible menopause-related changes in circulating insulin-like growth factor binding protein 3 (IGFBP-3) levels and their relationship with insulin-like growth factor I (IGF-I) plasma levels. Forty-three healthy women, aged 45-55 years, were studied (22 premenopausal and 21 postmenopausal, matched for age and body mass index); in all subjects plasma IGF-I and IGFBP-3 levels were measured by radioimmunoassay. No difference was found between mean IGFBP-3 plasma levels in the two groups studied (premenopausal 3.42 +/- 0.49 v postmenopausal 3.46 +/- 0.58 mg/l), while mean IGF-I levels were significantly lower in postmenopausal as compared with premenopausal women (136.7 +/- 37.86 v 175.7 +/- 51.91 ng/ml, p < 0.02). Multiple regression analysis showed no significant effect of age, body mass index and years since menopause on IGFBP-3 levels; however, considering the IGF-I/IGFBP-3 ratio as a possible parameter of circulating free somatomedin C, an inverse correlation was found with years since menopause (n = 43, r = -0.499, p < 0.001). We conclude that lack of oestrogen induces different effects on circulating IGF-I and IGFBP-3, possibly reflecting a real decrease in IGF-I activity.