Objectives To assess the changes in sex hormone levels with age and the relationship of sexual functioning to testosterone levels, evaluating serum testosterone levels and erectile function in men with lower urinary tract symptoms (LUTS).
Patients and methods The study included 213 men with LUTS (age range 31–78 years) who had no confirmed erectile dysfunction. Their serum total and free testosterone, and sex-hormone binding globulin (SHBG) levels were measured, and they completed the International Index of Erectile Function (IIEF) questionnaire.
Results The total and free testosterone levels decreased and SHBG increased with age, but only the change in free testosterone and SHBG were statistically significant. The correlation with age was closer for free testosterone (r = − 0.356, P < 0.001) than for SHBG (r = 0.177, P = 0.010). Regression analysis of the five domain scores of the IIEF and three hormonal levels, after correcting for age, showed that free testosterone level was significantly correlated with erectile function (r = 0.2136, P = 0.005) and orgasmic function (r = 0.179, P = 0.020), but SHBG levels were significantly correlated only with orgasmic function (r = − 0.154, P = 0.046). Total testosterone levels showed no significant correlation with any of the five domains of the IIEF.
Conclusions Of the sex hormone levels, the change in free testosterone correlated most closely with ageing and had the closest correlation with sexual activity. Contrary to previous reports, free testosterone and SHBG levels were significantly correlated with orgasmic function and/or erectile function rather than sexual desire. A complete study of sex hormone levels is needed to evaluate patients with erectile dysfunction.