 The aim of this study is to analyse urinary neurotrophin levels in healthy children. Urine samples will be collected at 3 different times of day morning, noon, and evening at urge sensation from all age groups of children who gained bladder control, i.e. from 3-18 years of age. Urinary levels of nerve growth factor NGF and brain-derived neurotrophic factor BDNF normalised to urinary creatinine will be analysed. Age and daytime related variations will be reported for both boys and girls. These results will contribute to understanding the role of neurotrophins in the physiology of lower urinary tract and pathophysiology of idiopathic and secondary hyperactive bladder in children. 