Objectives: To measure urinary nerve growth factor (NGF) levels in women with stress urinary incontinence (SUI) and overactive bladder symptoms (OAB) and to assess whether urinary NGF levels can be a biomarker of detrusor overactivity (DO) in women with mixed urinary incontinence.
Patients, subjects and methods: Urinary NGF levels were measured in 38 women with urodynamic SUI (USI) with OAB, in 26 with urodynamic DO but no SUI, in 21 with persistent USI after anti-incontinence surgery, in 15 with de novo DO, and in 31 normal control subjects. All participants had a video-urodynamic study for the differential diagnosis of the underlying causes of UI. Urinary NGF levels were measured using an enzyme-linked immunosorbent assay and were compared among all subgroups, and corrected using urinary creatinine (Cr) levels.
Results: The mean (sem) urinary NGF/Cr levels were low both in controls, at 0.06 (0.004) and in women with pure USI, at 0.056 (0.037) (P = 0.108). The NGF/Cr levels were significantly higher in women with mixed USI and DO, at 1.00 (0.244), than in controls (P < 0.001) and those with pure USI (P = 0.006), but were similar to the levels in women with pure DO, at 0.58 (0.17) (P = 0.058). The NGF/Cr levels were undetectable in women with persistent USI but were significantly higher in those with de novo DO, at 2.39 (0.90), after anti-incontinence surgery than in controls and those with USI. A urinary NGF/Cr level of >0.05 was found in 9% of women with USI, 77% with DO, 81% with mixed USI and DO, and 80% with de novo DO.
Conclusion: The urinary NGF level could be a potential biomarker of DO in women with mixed UI.