The relationships between sex hormones and sexual function in middle-aged and older European men.
O'Connor DB., Lee DM., Corona G., Forti G., Tajar A., O'Neill TW., Pendleton N., Bartfai G., Boonen S., Casanueva FF., Finn JD., Giwercman A., Han TS., Huhtaniemi IT., Kula K., Labrie F., Lean ME., Punab M., Silman AJ., Vanderschueren D., Wu FC.
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.