Total testosterone may not decline with ageing in Korean men aged 40 years or older

Objective It is generally believed that gonadal function in men declines with ageing. However, observations on ageing-related decrease in total testosterone (TT) are not consistent. The aim of this study is to examine the ageing-related changes of testosterone and to investigate the influence of the ageing-related factors on TT. Design Changes of TT with ageing were observed in longitudinal design in a single health promotion centre. Subjects A total of 220 Korean men aged =40 similar to years were included between 2002 and 2011. TT assay was repeated for all subjects, with an interval of =3 similar to years. Measurements Information of medical history and lifestyle habits was collected. Anthropometry and blood pressure were measured. TT, glucose, creatinine, highly sensitive C-reactive protein, liver enzymes and lipid profiles were tested. Results Mean TT level did not decline significantly with ageing during median 4.3 similar to years follow-up (18.1 vs 17.8 similar to nm, P similar to=similar to 0.439). Longitudinal change of TT was approximately similar to+similar to 0.8% per year. TT was negatively correlated with body mass index (BMI), waist circumference and glucose. With mixed effects model, diabetes (P similar to=similar to 0.038) and BMI (P similar to=similar to 0.007) affected TT level, but age and follow-up interval did not. Conclusions TT did not change significantly in 220 Korean men for a median 4.3 similar to years follow-up. TT was not influenced by the age and follow-up interval. BMI and diabetes mellitus affected TT decline.