Vitamin D Treat-to-Target Strategy for Children With Overactive Bladder-Wet

The purpose of this clinical trial is to investigate whether adding high-dose vitamin D (2,400 IU daily) to standard medical treatment (solifenacin combined with behavioral therapy) is more effective than standard treatment alone for children with overactive bladder-wet (OAB-wet). OAB-wet causes sudden urinary urges and frequent daytime or incontinence, which significantly impacts a child's quality of life and increases the family's caregiving burden. While solifenacin is a standard medication used to calm the bladder, many children do not achieve complete dryness. This study introduces the "Treat-to-Target" (T2T) approach, where clinicians and families set personalized "functional goals" (such as zero leakage) and monitor progress closely to adjust care. The study aims to answer the following questions: Does adding vitamin D help more children achieve their goal of "zero leakage" compared to standard treatment? Does vitamin D help repair bladder-related nerves, as measured by a specific marker in the urine? Does this combined approach reduce the family's expenses (like laundry costs and diaper use) and improve the child's self-esteem? Participants will be randomly assigned to one of two groups for 12 weeks: Intervention Group: Standard care (solifenacin + behavioral therapy) plus daily vitamin D (2,400 IU). Control Group: Standard care (solifenacin + behavioral therapy) alone. Researchers will evaluate symptoms, vitamin D levels, and nerve repair markers at 6 and 12 weeks to determine the best treatment strategy for these children.