Hypothalamic-pituitary-testicular axis disruptions in older men are differentially linked to age and modifiable risk factors: The European Male Aging Study

CONTEXT The cause of declining testosterone (T) in aging men and their relationships with risk factors are unclear. OBJECTIVE To investigate the relationships between lifestyle and health with reproductive hormones in aging men. DESIGN Baseline cross-sectional survey on 3200 community - dwelling men aged 40 - 79 yr from a prospective cohort study in 8 European countries. RESULTS Four predictors were associated with distinct modes of altered function:- Age: lower free T (FT) (-3.12 pmol/L/ yr, p/=25 - /=30 kg/m(2) (p <0.001 - 0.01, referent: BMI <25 kg/m(2)) with unchanged/decreased LH, indicating hypothalamus/pituitary dysfunction. Co-morbidity: lower TT (-0.80 nmol/L, p <0.01) with unchanged LH in younger men but higher LH in older men. Smoking: higher sex hormone binding globulin (SHBG) (5.96 nmol/L, p <0.001) and LH (0.77 U/L, p <0.01) with increased TT (1.31 nmol/L, p