The relationships between sex hormones and sexual function in middle-aged and older European men.

Context: Limited data are available exploring the associations between sex hormones, multiple domains of sexual functioning, and sexual function-related distress in nonpatient samples in Europe.

Objectives: The aim of the study was to investigate the relationships between serum testosterone (T), estradiol (E2), and dihydrotestosterone (DHT) and sexual function in a multicenter population-based study of aging in men.

Design: Using stratified random sampling, 2838 men aged 40-79 yr completed the European Male Ageing Study-Sexual Function Questionnaire and provided a blood sample for hormone measurements. T, E2, and DHT were measured using gas chromatography-mass spectrometry.

Setting: We conducted a community-based population survey in eight European centers.

Main Outcome Measures: Self-reported sexual function (overall sexual function, sexual function-related distress, erectile dysfunction, masturbation) was measured.

Results: Total and free T, but not E2 or DHT, was associated with overall sexual function in middle-aged and older men. E2 was the only hormone associated with sexual function-related distress such that higher levels were related to greater distress. Free T levels were associated with masturbation frequency and erectile dysfunction in the fully adjusted models, such that higher T was associated with less dysfunction and greater frequency. Moreover, there was a T threshold for the relationship between total T, sexual function, and erectile dysfunction. At T concentrations of 8 nmol/liter or less, T was associated with worse sexual functioning, whereas at T levels over 8 nmol/liter, the relationship came to a plateau.

Conclusions: These findings suggest that different hormonal mechanisms may regulate sexual functioning (T) vs. the psychological aspects (E2) of male sexual behavior. Moreover, there was a T threshold for overall sexual function such that at levels greater than 8 nmol/liter the relationship between T and sexual function did not become stronger.