Marriott RJ, Murray K, Hankey GJ, et al. - In this study population of relatively healthy middle-aged to older men, mean serum total testosterone levels were shown to be stable with ageing, while mean sex hormone-binding globulin (SHBG) levels increased. Over time, both total testosterone and SHBG levels were highly concordant.

• In this population-based longitudinal cohort study including community-dwelling men aged 40–69 years, longitudinal changes in serum testosterone and SHBG levels were assessed in middle-aged to older men, as well as concordance between baseline and follow-up values and links with concomitant changes in lifestyle and medical factors.

• A 4.3 years follow-up revealed a negligible mean change (±SE) in serum total testosterone level (+0.06 ± 0.03 nmol/L) whereas a rise in mean SHBG concentration (+3.69 ± 0.12 nmol/L) and decline in that of free testosterone (cFT) (−10.7 ± 0.7 pmol/L).

• For total testosterone, SHBG, and cFT, the concordance estimates were 0.67, 0.83, and 0.56, respectively.

• Alterations in serum total testosterone correlated with alterations in SHBG, and inversely with alterations in body mass index (BMI) and waist circumference and in SHBG with changes in BMI and waist circumference.