Decreased urinary nerve growth factor reflects prostatic volume reduction and relief of outlet obstruction in patients with benign prostatic enlargement treated with dutasteride.

OBJECTIVES: To examine urinary nerve growth factor before and after dutasteride treatment, and to analyze correlations between clinical parameters and change of urinary nerve growth factor in patients with benign prostatic enlargement.

METHODS: We prospectively studied 30 patients with benign prostatic enlargement who had not been satisfied with α-adrenergic antagonist monotherapy for more than 3 months. Before and 24 weeks after dutasteride add-on treatment, we assessed International Prostate Symptom Score, prostatic volume, filling cystometry and pressure-flow study. Urinary nerve growth factor was measured by enzyme-linked immunosorbent assay, and normalized to the urinary creatinine (nerve growth factor/creatinine) before and 24 weeks after dutasteride add-on treatment.

RESULTS: In baseline characteristics before dutasteride, there was no significant correlation between urinary nerve growth factor/creatinine and any clinical parameters including age, International Prostate Symptom Score, prostatic volume, presence of detrusor overactivity, detrusor pressure at maximum flow rate, bladder outlet obstruction index or bladder contractility index. Dutasteride significantly reduced prostatic volume (from 68 ± 31 mL to 49 ± 28 mL) and improved International Prostate Symptom Score (from 17.2 ± 8.7 to 13.1 ± 6.8), storage (from 8.0 ± 4.3 to 6.0 ± 2.9) and voiding symptom subscore of International Prostate Symptom Score (from 9.3 ± 5.7 to 7.1 ± 4.5). In urodynamic study, detrusor pressure at maximum flow rate (from 77 ± 32 cmH2 O to 59 ± 24 cmH2 O) and bladder outlet obstruction index (from 62 ± 32 to 42 ± 27) were significantly decreased after dutasteride treatment. Urinary nerve growth factor/creatinine was significantly decreased after dutasteride from 2.61 ± 2.50 to 1.64 ± 1.68. The change of urinary nerve growth factor/creatinine significantly correlated only with the change of prostatic volume (r = 0.38) and bladder outlet obstruction index (r = 0.36).

CONCLUSIONS: Urinary nerve growth factor decreases in association with reduction of prostatic volume and relief of bladder outlet obstruction. Urinary nerve growth factor might be useful as a biomarker to monitor the improvement of bladder outlet obstruction in patients with benign prostatic enlargement.