Bladder overactivity is a common problem affecting the social functioning of children. Overactive bladder dry (OAB-dry) is a term (one not utilised by the International Children’s Continence Society) and refers to patients who are experiencing frequency, urgency and nocturia symptoms without urgency incontinence. Anticholinergics are usually utilised when urotherapy proves inadequate in symptom control. There is evidence linking vitamin D insufficiency and elevated rates of lower urinary tract symptoms. Recent studies have shown that vitamin D supplementation (VDS) may improve urinary tract symptoms in specific adult populations. The authors conducted a pilot study and noted that around 90% of children with OAB-dry had vitamin D levels below 35ng/ml and high-dose VDS plus standard urotherapy was effective in reducing voiding frequencies in these children after eight weeks of intervention. To validate their findings, they designed a randomised control trial (RCT) to evaluate the efficacy and safety of this approach. The RCT was conducted January to June 2023 at the National Clinical Research Centre for Child Health and Disease (Chongqing). Children aged 5-18 diagnosed with OAB-dry and vitamin D level below 35ng/ml were enrolled. Participants were signed to: 1) high-dose VDS plus urotherapy, 2) Solifenacin (5-10mg) plus urotherapy, or 3) urotherapy alone for eight weeks. Evaluation was undertaken upon enrolment, after one month and after two months. Four hundred and sixty-seven participants were assessed for eligibility and 303 were randomly assigned to one of the three study groups. Ninety-three percent completed the eight-week intervention and post-treatment assessment. VDS and urotherapy resulted in superior outcomes for voiding frequency, urgency scores, quality of life scores and paediatric lower urinary tract symptom scores compared to solifenacin plus urotherapy or urotherapy alone. Vitamin D supplementation was well tolerated. Although the publication is initially interesting, the authors state that inadequate vitamin D levels might impede gastrointestinal motility and hence result in constipation (potentially elucidating the mechanism between high-dose VDS and alleviation of OAB symptoms). The authors purely looked at voiding frequency and urgency scores rather than assessing voided volumes. The authors did not control for constipation. Vitamin D may also have a positive psychiatric effect and potentially function via interaction with bladder receptors. Obviously, the trial would benefit from a fully blinded strategy (as this could lead to bias) and a placebo group. Further work is as yet required.
Can you boost your bladder with vitamin D?
Reviewed by Neil Featherstone
Efficacy and safety of high-dose vitamin D supplementation vs solifenacin or standard urotherapy for overactive bladder dry in children: a randomized clinical trial.
CONTRIBUTOR
Neil Featherstone
Cambridge University Hospitals NHS Foundation Trust (Addenbrookes Hospital).
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