The IGF-system in healthy pre- and postmenopausal women: relations to demographic variables and sex-steroids.
Plasma insulin-like growth factor (IGF)-I, free IGF-I and -II, IGF-binding protein (IGFBP)-1, -2, and -3 together with IGFBP-3 protease activity were measured in 114 postmenopausal and 39 premenopausal healthy women. For each parameter, the mathematical distribution was characterised, and the normal range for pre- and postmenopausal women described, together with correlations to demographic variables and sex-steroids (postmenopausal women). Postmenopausal women had lower levels of plasma IGF-I (P<0.001) and free IGF-I (P<0.001) compared to premenopausal women, while plasma IGFBP-2 (P<0.05) and immunoreactive IGFBP-3 (P<0.001) were higher in postmenopausal women. Free IGF-I (but none of the other parameters) was significantly lower in postmenopausal smokers compared to non-smokers (P<0.05).IGF-I and -II both correlated positively to height (r=0.203, P<0.05 and r=0.198, P<0.05, respectively), while IGF-II correlated positively to weight (r=0.250, P<0.01). Plasma IGF-I correlated positively to androstenedione (r=0.292, P<0.01) and dehydroepiandrosterone sulphate (DHEAS, r=0.202, P<0.05), while a significant positive correlation was observed between IGF-II on the one side and oestradiol (E(2), r=0.227), oestrone sulphate (E(1)S, r=0.238) and androstenedione (r=0.213) on the other side (P<0.05 for all). Our results support a relation between sex-steroids and IGF-I and -II in healthy postmenopausal women. The lower levels of total and free IGF-I in postmenopausal compared to premenopausal women indicate lower bioavailability of this growth factor in elderly females.
Department of Oncology, Haukeland University Hospital, N-5021 Bergen, Norway.
Svein I
SI
Helle
Dagfinn
D
Ekse
Jeff M P
JM
Holly
Per E
PE
Lønning
D000368:Aged; D003710:Demography; D005260:Female; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000378:metabolism*; D008875:Middle Aged; D017698:Postmenopause; D017697:Premenopause; D012907:Smoking / Q000097:blood; D013002:Somatomedins / Q000378:metabolism*
D018969:Insulin-Like Growth Factor Binding Proteins; D013002:Somatomedins