['Urinary nerve growth factor (NGF) levels have been shown to be increased in patients with symptoms of overactive bladder (OAB). This study was designed to measure the urinary NGF levels in patients with bladder outlet obstruction (BOO) with or without OAB and to determine whether urinary NGF can serve as a biomarker for OAB.', 'Urinary NGF levels were measured in 38 male control subjects without lower urinary tract symptoms and 153 patients with BOO. The diagnosis of BOO was further classified as BOO/non-OAB (n = 21), BOO/OAB (n = 25), BOO with urodynamically confirmed detrusor overactivity (BOO/DO, n = 47), and BOO/OAB in patients who had received successful medical treatment (n = 60). The urinary NGF levels were measured by enzyme-linked immunosorbent assay and compared among the different groups. The total urinary NGF levels were normalized to the concentration of the urinary creatinine (NGF/Cr) level.', 'The urinary NGF/Cr levels were very low in the control group (mean +/- standard error 0.005 +/- 0.003) and in patients with BOO/non-OAB (0.017 +/- 0.009) and significantly greater in patients with BOO/OAB (0.81 +/- 0.31) and BOO/DO (0.80 +/- 0.13). The urinary NGF/Cr levels were not significantly different between the BOO/OAB and BOO/DO groups; however, the urinary NGF/Cr levels returned to normal levels (0.059 +/- 0.021) after successful relief of OAB symptoms with medical treatment.'] Are urinary nerve growth factor levels increased in patients with bladder outlet obstruction with overactive bladder symptoms and reduced after successful medical treatment?