Total testosterone may not decline with ageing in <scp>K</scp>orean men aged 40 years or older

Abstract

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 years were included between 2002 and 2011. TT assay was repeated for all subjects, with an interval of ≥3 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 years follow-up (18·1 vs 17·8 nm, P = 0·439). Longitudinal change of TT was approximately + 0·8% per year. TT was negatively correlated with body mass index (BMI), waist circumference and glucose. With mixed effects model, diabetes (P = 0·038) and BMI (P = 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 years follow-up. TT was not influenced by the age and follow-up interval. BMI and diabetes mellitus affected TT decline.