To evaluate the impact of serum vitamin D level on male lower urinary tract symptoms (LUTS).
Men with LUTS who visited the outpatient clinic of the urology department at one of two hospitals between March 2014 and April 2017 were eligible for inclusion in the study. The impact of vitamin D on LUTS was evaluated using multivariate analysis to adjust for age, body mass index, prostate-specific antigen, testosterone, glycated haemoglobin, physical activity and prostate volume. To exclude the effect of seasons, we also analysed the impact during each season.
Vitamin D level was lowest in winter. According to the International Prostate Symptom Score (IPSS) and Overactive Bladder Symptom Score (OABSS), the severity of LUTS peaked in winter. There were no seasonal differences between prostate volume, maximum urinary flow rate (Qmax) and post-void residual urine volume (PVR). For all patients, multivariate analysis showed that lower vitamin D level was significantly associated with higher total OABSS, whereas it was not associated with prostate volume, Qmax , PVR or total IPSS. In winter, lower vitamin D level was significantly associated with higher total OABSS based on multivariate analysis, whereas it was not during other seasons. In patients with vitamin D deficiency, the total OABSS significantly decreased after vitamin D replacement. The greatest improvement in total OABSS was associated with lower pre-treatment total OABSS and higher post-treatment vitamin D level.
Vitamin D deficiency in men with LUTS may play a role in aggravated overactive bladder (OAB) symptoms, especially in winter. Increasing vitamin D level in patients with vitamin D deficiency appears to alleviate OAB symptoms.