Serum insulin-like growth factor binding protein profiles in postmenopausal women: their correlation with bone mineral density.

Abstract

The objective of this study was to evaluate the relationship between serum insulin-like growth factor binding protein profiles and bone mineral density measurements and biochemical markers of bone turnover in postmenopausal women. Sera from 37 normal healthy postmenopausal women and 14 postmenopausal women with osteoporosis were analyzed for insulin-like growth factor binding proteins and osteocalcin by Western ligand blotting and radioimmunoassay, respectively. Bone mineral density measurements were performed by dual-energy x-ray absorptiometry. Urinary calcium and creatinine excretion were also determined. The data were analyzed statistically by analysis of variance and the least-squares method. The serum insulin-like growth factor binding protein-2 ratio (insulin-like growth factor binding protein-2 intensity/total insulin-like growth factor binding protein intensity) in postmenopausal women with osteoporosis was significantly higher (p < 0.02) than that in normal healthy postmenopausal women, but the serum insulin-like growth factor binding protein-3 ratio in women with osteoporosis was significantly lower (p < 0.01). The serum insulin-like growth factor binding protein-2 ratio correlated negatively with the bone mineral density of the lumbar spine (p < 0.0001), femoral neck (p < 0.05), trochanter (p < 0.01), and Ward's triangle (p < 0.05), but there was a significant positive correlation between the serum insulin-like growth factor binding protein-3 ratio and the bone mineral density of the lumbar spine (p < 0.001) and trochanter (p < 0.05). No correlations between serum insulin-like growth factor binding protein levels or serum ratios and biochemical markers of bone turnover were noted. The measurement of serum insulin-like growth factor binding protein profiles might be useful in identifying postmenopausal women at risk for osteoporosis.