Pre-treatment serum testosterone level can be a useful factor to predict the improvement in bladder outlet obstruction by tadalafil for male patients with lower urinary tract symptoms induced by benign prostatic obstruction.

To investigate possible pre-treatment factors related to the therapeutic effect of tadalafil on bladder outlet obstruction (BOO). Eighty untreated outpatients with lower urinary tract symptoms (LUTS) due to BOO received 5 mg tadalafil daily for 12 months. Subjective symptoms and objective findings were evaluated before and 12 months after treatment. At 12 months, the patients were divided into two groups according to an improvement grade in BOO index (BOOI). Patient characteristics including age, serum total testosterone level (TT), PSA, and prostate volume, and subjective and objective parameters on LUTS were set as candidates of pre-treatment factors, and the parameters that influenced the improvement of BOO were statistically analysed. A total of 69 patients with mean age of 69.8 years and mean prostate volume of 48.8 mL were included. Subjective symptoms and BOOI were significantly ameliorated after 12 months. In terms of an improvement of BOOI, 30 patients (43.5%) showed insignificant improvement in BOO, whereas 39 patients (56.5%) exhibited excellent improvement. Comparison of pre-treatment factors between the groups showed that TT was the only independent predictor related to the improvement in BOO. The improvement of BOO was significantly better in patients with higher TT. Pre-treatment TT was considered to be a useful predictor of therapeutic effects of tadalafil for BOO.