The relationship between serum insulin - like growth factor binding proteins profiles and bone mineral density in women without ovarian function

Moon, Shin Yong; Choi, Young Min; Kim, Seok Hyun; Lee, Jin Yong; Kim, Jung Gu; Shin, Chan Soo; Suh, Chang Seok; Kim, Seong Yeon

Abstract

The insulin-like growth factor(IGF)s are believed to play an important role in the maintenance of bone mass. The IGFs are found complexed with high affinity to a family of IGF-binding protein(IGFBP)s in the circulation. It is known that IGFBPs are involved in the transport of IGFs to tissues and modulate IGFs actions at local tissue The purposes of this study were to compare serum IGFBPs profiles in natural menopausal women with and without osteoporosis and in osteoporotic and nonosteoporotic women with premature menopause and to evaluate the relationship between serum IGFBPs profiles and bone mineral density(BMD) in women without ovarian function. Serum IGFBPs were measured by western ligand blot and immunoradiometric assay. The relative levels and proportions of serum IGFBP-2 measured by western ligand blot in natural menopausal women with osteoporosis(n=20) significantly increased compared to nonosteoporotic women(n= 20), whereas relative levels of serum IGFBP-3 in natural menopausal women with osteoporosis decreased. No significant differences in the relative levels of serum IGFBPs between osteoporotic(n=8) and nonosteoporotic women(n=10) with premature menopause were noted. The IGFBP-3 levels determined by immunoradiometric assay in women without ovarian function(n= 69) showed a similiar trend. The relative proportions of serum IGFBP-2 in osteoporotic women without ovarian function were signifcantly higher than those in nonosteoporotic women whereas relative levels of serum IGFBP-3 in osteoporotic women with natural menopause decreased. The relative levels and proportions of serum IGFBP-2 in women without ovarian function correlated negatively with BMD of lumbar spine, trochanter and Ward's triangle but there were significant positive correlations between levels and relative proportions of serum IGFBP-3 and BMD of above sites. No significant correlations between relative levels and proportions of serum IGFBP-1, IGFBP-2 and BMD were noted. Our data indicate that serum IGFBP profiles might be useful in identifying women without ovarian funcion at risk for osteoporosis,