RELATIONSHIP BETWEEN CIRCULATING INSULIN-LIKE GROWTH-FACTOR COMPONENTS AND SEX-HORMONES IN A POPULATION-BASED SAMPLE OF 50 TO 80-YEAR-OLD MEN AND WOMEN

There is a large body of evidence that points to a systemic link betwe en the somatotropic axis and sex hormones, but epidemiologic data on t he interactions between the two hormonal systems are still missing. We examined here the associations between the plasma levels of insulin-l ike growth factor (IGF) I, IGF-II, IGF-binding protein 3 (IGFBP-3), an d sex hormones in a population-based sample of 486 men and women, aged 50-80 yr. The strongest association was an age-independent inverse co rrelation between all three circulating IGF components and sex hormone -binding globulin (SHBG), the major testosterone-binding protein in pl asma. Consistent with this, bio-available (non-SHBG-bound) but not tot al testosterone levels were positively associated with the IGF system in men, and 3 alpha-androstanediol glucuronide was positively correlat ed with circulating IGFs in women. Moreover, part of the correlation b etween the circulating IGF system and bone mineral density at the femu r and the calcaneus could be accounted for by SHBG. Our data suggest t hat sex hormones and the GH/IGF system are significantly interrelated in the elderly population. These hormonal interactions may play an imp ortant role in human aging and the pathogenesis of age-related disease s.