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.

Summary: Onion (Allium cepa L.) and quercetin protect against oxidative damage and have positive effects on multiple functional parameters of spermatozoa, including viability and motility. However, the associated underlying mechanisms of action have not yet been identified. The aim of this study was to investigate the effect of onion peel extract (OPE) on voltage‐gated proton (Hv1) channels, which play a critical role in rapid proton extrusion. This process underlies a wide range of physiological processes, particularly male fertility. The whole‐cell patch‐clamp technique was used to record the changes in Hv1 currents in HEK293 cells transiently transfected with human Hv1 (HVCN1). The effects of OPE on human sperm motility were also analyzed. OPE significantly activated the outward‐rectifying proton currents in a concentration‐dependent manner, with an EC₅₀ value of 30 μg/mL. This effect was largely reversible upon washout. Moreover, OPE induced an increase in the proton current amplitude and decreased the time constant of activation at 0 mV from 4.9 ± 1.7 to 0.6 ± 0.1 sec (n = 6). In the presence of OPE, the half‐activation voltage (V_1/2) shifted in the negative direction, from 20.1 ± 5.8 to 5.2 ± 8.7 mV (n = 6), but the slope was not significantly altered. The OPE‐induced current was profoundly inhibited by 10 μm Zn²⁺, the most potent Hv1 channel inhibitor, and was also inhibited by treatment with GF109203X, a specific protein kinase C (PKC) inhibitor. Furthermore, sperm motility was significantly increased in the OPE‐treated groups. OPE exhibits protective effects on sperm motility, at least partially via regulation of the proton channel. Moreover, similar effects were exerted by quercetin, the major flavonoid in OPE. These results suggest OPE, which is rich in the potent Hv1 channel activator quercetin, as a possible new candidate treatment for human infertility.