Insulin-Like Growth Factors I and II: Aging and Bone Density in Women*

Abstract Serum concentrations of insulin-like growth factors (IGF) were measured by RIA in 57 normal women, ages 30 - 90 yr, and in 29 untreated women with postmenopausal osteoporosis and vertebral compression fractures, ages 55 - 75 yr. These values were correlated with bone mineral density (BMD) of the distal and midradius assessed by single photon absorptiometry and of the lumbar spine assessed by dual photon absorptiometry as well as serum and urinary calcium, phosphorus, creatinine, alkaline phosphatase, immunoreactive PTH, urinary hydroxyproline, and creatinine clearance. Serum IGF-I levels declined markedly with age (r = −0.47, P < 0.001). Serum IGF-II levels decreased only slightly with age, and this decrease was not statistically significant. Although BMD at all three scanning sites also declined significantly with age, neither serum IGF-I nor II concentrations correlated with BMD when age was held constant. In women with postmenopausal osteoporosis, serum IGF-I and II did not differ from the con...