Nocturnal Urine Production is Central to the Pathogenesis of Nocturia in Patients with the Nocturnal Polyuria Syndrome
Thomas F. Monaghan, MD Candidate1, Christina W. Agudelo, MD Candidate1, Syed N. Rahman, MD Candidate1, Kyle P. Michelson, MD1, Jason M. Lazar, MD1, Karel Everaert, MD, PhD2, Jeffrey P. Weiss, MD1, Donald L. Bliwise, PhD3.
1SUNY Downstate Health Sciences University, Brooklyn, NY, USA, 2Ghent University Hospital, Ghent, Belgium, 3Emory University School of Medicine, Atlanta, GA, USA.
BACKGROUND: Fundamentally, nocturia is driven by a mismatch between nocturnal urine production (NUP) and bladder capacity, and the degree of discordance between these two variables strongly correlates with nocturia severity (Avulova, et al, Scand J Urol, 2015). By definition, patients with nocturnal polyuria [NP] in the absence of identifiable contributory comorbidities (termed the Nocturnal Polyuria Syndrome [NPS]) incur excess NUP, but bladder capacity in these patients remains poorly characterized. This study compares voided volumes (as a proxy for functional bladder capacity) in nocturia patients with vs. without NPS.
METHODS: Retrospective analysis of voiding diaries showing ≥2 nocturnal void(s) from men aged ≥18 years at an outpatient urology clinic. Patients with secondary causes of NP (diuretic use, sleep apnea, heart failure, edema, kidney disease, and diabetes insipidus) were excluded. Included patients were divided into 2 cohorts by NP status (NUP >90 vs. ≤90 mL/h). The number of nocturnal voids (NV), 24-h maximum voided volume (MVV), and nocturnal MVV (NMVV) were compared between groups using the Wilcoxon Rank-sum test to determine significance.
RESULTS: Patients with (n=49) vs. without (n=60) NPS demonstrated greater NV (3 [2-4] vs. 2 [2-3] voids, p=0.030), MVV (375 [300-480] vs. 208 [173-300] mL, p<0.001), and NMVV (300 [260-460] vs. 180 [125-240] mL, p<0.001).
CONCLUSIONS: Patients with vs. without NPS demonstrated more severe nocturia despite greater functional bladder capacity. Taken together, these results suggest that excess NUP (opposed to diminished bladder capacity) is the primary mechanism underlying the production-storage mismatch in NPS. Patients with nocturia owing to NPS may particularly benefit from behavioral/pharmacologic interventions targeting nocturnal urine volume.
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