Sheng et al (Neurourology and Urodynamics 2017; DOI: 10.1002/nau.23210) presented a meta-analysis based on 17 publications to show that urinary nerve growth factor (NGF) may be a useful biomarker for overactive bladder syndrome (OAB). Unfortunately, 13 of the 17 studies used an unspecifc enzyme-linked immunosorbent assay (ELISA), the Promega NGF Emax Immunoassay, to quantify NGF in urine. This assay did not detect NGF in urine, but other urinary components, such as immunoglobulin G, and in 2014, it was withdrawn from the market. With other NGF-ELISAs, urinary NGF concentrations were found to be below detection level for both, OAB and healthy controls. Currently, ELISA techniques are not sensitive enough to detect NGF in urine, and urinary NGF cannot be used as a biomarker for OAB.
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