Age related secretary pattern of growth hormone, insulin-like growth factor-I & insulin-like growth factor binding protein-3 in postmenopausal women

Background & objectives: After menopause in women, loss of bone density increases rapidly with estrogen deficiency. Evidence has revealed that this deficiency may be directly correlated with growth hormone (GH) level declining with age. The present study was designed to evaluate the age dependant patterns of GH, insulin-like growth factor-1 (IGF1-1) and insulin-like growth factor binding protein-3 (IGFBP-3) endogenous secretion in postmenopausal women. Methods: During this prospective study in a 12-month period, 150 postmenopausal women were enrolled who were referred to the densitometry unit of bone research centre of Tabriz University of Medical Sciences for assessing bone mineral density. Serum levels of basal and clonidine stimulated GH were measured using radioimmunoassay while IGF-1 and IGFBP-3 were measured by ELISA. Post stimulation over 3 to 6 fold increase in GH over the baseline level was considered normal response and less increase was considered abnormal. Results: There were no significant differences in the mean levels of GH0, GH60 and GH90 in different age groups of postmenopausal women. No significant difference in the mean IGFBP-3 and IGF-1 levels was seen in different age groups of postmenopausal women. The number of postmenopausal women with abnormal response to stimulation by clonidine in 61-70 and > 70 yr age groups was higher than in other groups (P<0.05). Interpretation & conclusions: Despite the higher rate of abnormal response to stimulation by clonidine in women aged more than 60 yr, the current study showed no significant correlation between age, and the basal and stimulated GH secretion rate and serum levels of IGF-1 and IGFBP-3 in postmenopausal women.