Relation Between Secretory Status of Growth Hormone, Serum Concentration of Insulin-like Growth Factor I, and Insulin-like Growth Factor Binding Protein 3 with Bone Mineral Density in Postmenopausal Women

Although the decline in sex steroid levels, particularly estradiol, may be largely responsible for age-related bone loss and osteoporotic fractures in older women, the insulin-like growth factor (IGF) system may also play a key role. This study aimed at evaluating the relation between the secretory status of growth hormones (GH), insulin-like growth factor I (IGF-I) and Insulin- like growth factor binding protein 3 (IGFBP3) and bone mineral density (BMD) in postmenopausal women. Materials Methods: In a descriptive crosssectional study, 150 postmenopausal healthy women were selected from among 1328 patients, referred to Tabriz Sina Hospital for bone densitometry, and divided into three groups according to their bone mineral density (BMD) (normal, osteopenic and osteoporotic). The GH response to provocation by clonidine was assessed in all patients. Results: One hundred and fifty patients with a mean age of 65.6±6.6 years, were enrolled in this study. The impaired GH response to provocation by clonidine was significantly more common in the group with osteoporosis compared to their healthy and osteopenic counterparts (72% vs. 56% and 44%, respectively; p=0.018). Mean levels of serum IGF-I and IGFBP3 were not significantly different in healthy, osteopenic and osteoporotic patients (55.4±20.7 μg/L, 57.5±21.7 μg/L, and 56.7±19.2 μg/L; p=0.880 and 2648.3±786.4 ng/ml, 2374.0±707.2 ng/ml, and 2613.5±1023.6 ng/ml;p=0.217, respectively). There was no strong correlation between the level of serum IGF-I or IGFBP3 and T-Score (r=-0.026, p=0.753 for IGF-1 and r=0.046, p=0.575 for IGFBP3). Conclusion: The results of this study showed that the defective release of GH is more prevalent in postmenopausal women suffering from osteoporosis; such a defect was not observed regarding serums of IGF1 and IGFBP3. Prescription of supplementary doses of synthetic GH might be beneficial in this population.