Sirisopana K.Piyawannarat S.Ketsuwan C.Arpornsujaritkun N.Kantachuvesiri S.Kijvikai K.Kongcharoensombat W.Phengsalae Y.Matang W.Sangkum P.Mahidol University2026-06-262026-06-262026-01-01Frontiers in Transplantation Vol.5 (2026)https://repository.li.mahidol.ac.th/handle/123456789/117528Objective – This study aimed to prospectively evaluate changes in erectile function and sex hormone levels, including free and bioavailable testosterone, in male end-stage renal disease (ESRD) patients before and at various time points after kidney transplantation (KT). Methods – Male ESRD patients aged 18–70 years who underwent living KT were enrolled between September 2019 and April 2021. Participants completed the International Index of Erectile Function (IIEF-5) and Aging Male Symptoms (AMS) questionnaires one day before KT and at one, six, and 12 months post-transplant. Sex hormones, including testosterone, sex hormone-binding globulin (SHBG), albumin, FSH, and LH, were measured at the same intervals. Free and bioavailable testosterone levels were calculated using a verified calculator. Results – Twenty-eight male patients were enrolled, with a mean age of 43.5 years. The IIEF-5 scores significantly improved at six months after KT (p = 0.006) and were maintained over one year. Patients with a dialysis duration of one to three years showed significant improvement in IIEF-5 scores (p = 0.019), whereas those on dialysis for more than three years did not demonstrate significant changes. AMS scores significantly decreased (improved) starting from the first month post-KT (p < 0.001). Regarding hormones, bioavailable testosterone increased significantly six and 12 months after KT, while free testosterone revealed non-significant increases. LH levels decreased at one month post-KT (p < 0.001) and remained reduced throughout the study. Conclusion – Successful KT significantly enhanced erectile function, particularly in patients with a dialysis duration of less than three years, with significant improvements observed after six months. The increase in bioavailable testosterone and the reduction in LH levels, alongside improved AMS scores, may reflect the restoration of testicular functioning following transplantation. Clinical Trial Registration – https://www.thaiclinicaltrials.org/show/TCTR20181123003, identifier: TCTR20181123003.MedicineImmunology and MicrobiologyArticleSCOPUS10.3389/frtra.2026.18121052-s2.0-10504223822128132440