Influence of gender on serum growth hormone, insulin-like growth factor-I and its binding protein-3 during aging

The serum concentrations of insulin-like growth factors-I (IGF-I), insulin-like growth factor binding protein-3 (IGFBP-3) and growth hormone (GH) are related to body composition, function and metabolism, and are influenced by the aging process. This study was to investigate the influence of gender on serum concentrations of IGF-I, IGFBP-3 and GH in middle and old age subjects.

Sixty healthy volunteers (male 35, female 25, 36-70 years) were divided into < or = 50 and > 50 years groups, based on gender. Women > 50 years were post-menopause. IGF-I, IGFBP-3, and GH were determined by immunoradiometric assay.

IGF-I was shown to be negatively correlated with age (women r = -0.62, p < 0.001; men r = -0.38, p < 0.05), whereas there was no correlation between IGF-I and GH values. Women > 50 years showed a significant reduction in IGF-I values than women < or = 50 years (p < 0.01). Women > 50 years showed smaller IGF-I/IGFBP-3 molar ratios (0.177998 +/- 0.039404) than men of same age group (0.228326 +/- 0.050979, p < 0.01) and women < or = 50 years (0.247667 +/- 0.069411, p < 0.01). Age was shown to positively correlate with GH/IGF-I (r = 0.49, p < 0.05) and GH/IGFBP-3 ratios (r = 0.40, p < 0.05) in women.

The influence of aging on serum concentrations of IGF-I is more remarkable in women than in men. Menopause causes reduction of IGF-I/IGFBP-3 molar ratio. Women have the trend of progressive hypoactivity of GH to stimulate IGF-I and IGFBP-3 secretions with age.