Oral Presentation Annual Meetings of the Endocrine Society of Australia and Society for Reproductive Biology and Australia and New Zealand Bone and Mineral Society 2016

Cross-sectional and longitudinal determinants of serum sex hormone binding globulin (SHBG) in community-dwelling men: the Men Androgen Inflammation Lifestyle Environment and Stress (MAILES) study (#111)

Prabin Gyawali 1 2 , Sean A. Martin 2 , Leonie K. Heilbronn 1 , Anne W. Taylor 3 , Robert JT. Adams 4 , Peter D. O’Loughlin 5 , Gary A. Wittert 1 2
  1. School of Medicine, University of Adelaide, Adelaide, South Australia, Australia
  2. Freemasons Foundation Centre for Men’s Health, University of Adelaide, Adelaide, South Australia, Australia
  3. Population Research and Outcomes Studies, University of Adelaide , Adelaide, South Australia, Australia
  4. The Health Observatory, University of Adelaide, Queen Elizabeth Hospital, Woodville, South Australia, Australia
  5. Chemical Pathology, SA Pathology, Adelaide, South Australia, Australia

Objective: Variation in circulating sex hormone binding globulin (SHBG) levels are subject to regulation from a variety of hormonal, metabolic, nutritional, and genetic factors. Data on the regulation of male SHBG levels have largely been derived from epidemiological studies, with notable design limitations (e.g. smaller, non-representative samples, age ranges, limited control of related covariates, and cross-sectional design).

Material and Methods: SHBG (measured by chemiluminescent immunoassay) was examined in relation to body composition (DEXA), metabolic state (glucose, insulin, triglycerides), thyroid hormones (thyroxine (fT4)), sex steroids (testosterone (T), oestradiol(E2)), pro-inflammatory cytokines (Il-6, TNF-α, MPO & eSel), and socio-demographic, lifestyle, and other health-related factors at baseline and after 5 years in a randomly-selected cohort of community-dwelling men aged 35-80 at enrolment (n=2563). After excluding men with illness or on medications known to affect SHBG (n=220), data from 1738 men were available at baseline and 1428 at follow-up. Multiple stepwise linear regression models were used to estimate the cross-sectional and longitudinal determinants of SHBG.

Results: At baseline, there were independent positive associations between SHBG and age (β=.220, p=.000), T (β=.434, p=.000) and inverse associations between SHBG and triglycerides (β=-.099, p=.023) and E2 (β=-.119, p=.003), with no significant relationships, observed for smoking, physical activity, abdominal fat mass, insulin, glucose, ALT, fT4, IL6, TNF-α, MPO or eSel. Longitudinal multi-adjusted analyses revealed an inverse association of change in SHBG levels with baseline triglycerides (β=-.125, p=.000), abdominal fat mass (β=-.103, p=.006), and positive associations between SHBG and age (β=.404, p=.000), physical activity (β=.065, p=.043), fT4 (β=.091, p=.005) and T (β=.567, p=.000), with no significant effect observed for smoking, insulin, glucose, ALT, E2, IL6, TNF-α, MPO or eSel.

Conclusion: SHBG has an inverse relationship with triglycerides and a positive relationship with serum testosterone in community-dwelling men. SHBG levels reflects the metabolic state, in particular factors relating to lipid metabolism.