Eligibility Criteria:
Inclusion Criteria
* Children aged 5-18 years diagnosed with PMNE-defined as intermittent urinary incontinence during sleep in a children who are never dry for more than 6 months and have no other lower urinary tract symptoms-according to the latest International Children's Continence Society guidelines, presenting at outpatient urology clinics.
* Serum vitamin D level below 30 ng/mL.
* Written informed consent obtained from each participant and their guardian.
* Adequate psychological and cognitive function, no communication barriers, and ability to accurately report symptoms and potential adverse reactions during treatment.
Exclusion Criteria
* Urological malformations or serious urological disease, such as hypospadias, cryptorchidism, posterior urethral valves, vesicoureteral reflux, neurogenic bladder, urinary tumors, urinary stones, or bladder/urethral injuries.
* Neurological disorders, including epilepsy, spinal cord injury or dysplasia, spinal embolism syndrome, multiple sclerosis, autism spectrum disorder, or attention-deficit/hyperactivity disorder.
* Endocrine diseases, such as diabetes mellitus or hyperthyroidism.
* Severe systemic disease, including significant cardiac disease, renal or hepatic insufficiency, pulmonary disease, bone deformities, gastrointestinal disorders, or inherited metabolic disorders.
* Conditions predisposing to sleep apnea, such as adenoid or tonsillar hypertrophy, deviated nasal septum, craniofacial abnormalities, or central sleep apnea.
* History of gastrointestinal or urological surgery.
* Use of anticonvulsant, antiepileptic, corticosteroid, or anti-tuberculosis medications.
* History of hypercalcemia, hyperphosphatemia, or renal rickets.
* Unexplained hematuria or urinary tract infection within the past year.
* Allergy to vitamin D formulations.
* Concurrent participation in other clinical studies.
* Unwillingness to participate or poor anticipated follow-up compliance.