Diagnosing Small Bladder Capacity from Nocturnal Voiding Diary Data in Men with Nocturia

Monaghan T1, Khargi R1, Miller C1, Agudelo C1, Michelson K1, Lazar J1, Weiss J1

Research Type


Abstract Category


Abstract 81
ePoster 2
Scientific Open Discussion Session 8
Voiding Diary Nocturia Voiding Dysfunction
1. SUNY Downstate Health Sciences University

Thomas F Monaghan



Hypothesis / aims of study
The pathogenesis of nocturia centers on a fundamental mismatch between nocturnal urine production and small bladder storage capacity (SBC). A 24-hour voiding diary is the gold standard for differentiating these mechanisms, but requires careful documentation of the timing and volume of every void across a 24-72-hour period, such that patient adherence remains a pervasive obstacle in the real-world clinical setting. Assessment of voiding diary data from the hours of sleep can, in of itself, support a diagnosis of nocturnal polyuria (NP) on the basis of nocturnal urine production rate [1]. Conversely, a diagnosis of SBC from the voiding diary is typically based on the single largest volume across the diary record, referred to as the 24-hour ‘maximum voided volume’ (MVV). While the nocturnal MVV (NMVV) can, by definition, be used to exclude SBC, the utility of this parameter to rule in a diagnosis of SBC remains unclear. Accordingly, this study aims to determine the specificity of NMVV for SBC among men with nocturia.
Study design, materials and methods
Analysis of voiding diaries from men aged ≥18 years who were treated for lower urinary tract symptoms at an outpatient urology clinic from 2008-2019. Local Institutional Review Board approval with a waiver of informed consent was granted for retrospective analysis of routinely collected institutional data. Complete voiding diaries showing clinically-significant nocturia (≥2 nocturnal voids) were included for analysis. Included diaries were stratified based on the presence/absence of SBC (defined as a 24-hour MVV ≤200 ml) [2] and positive/negative nocturnal test for SBC (defined as NMVV ≤200 ml). Subgroup analyses were subsequently performed in patients with and without comorbid NP (defined as a nocturnal urine production rate >90 ml/hour) [1,3]. Specificities of the nocturnal test for SBC were calculated for each grouping.
SBC was present in 98 (27.5%) of the 356 voiding diaries which met the criteria for inclusion. Among voiding diaries without SBC, the nocturnal test was truly negative (i.e., NMVV >200 ml) in 225 cases and falsely positive (i.e., NMVV ≤200) in 33 cases, corresponding to 87.2% specificity. In the presence of NP (n=179), the nocturnal test for SBC was truly negative in 158 cases and falsely positive in 8 cases, with a specificity of 95.2%. In the absence of NP (n=177), the nocturnal test for SBC was truly negative in 67 cases and falsely positive in 25 cases, corresponding to 72.8% specificity.
Interpretation of results
By definition, NMVV >200 ml mathematically rules out a voiding diary-based diagnosis of SBC, but SBC cannot necessarily be excluded when NMVV is ≤200 ml. The major finding of the present study is that NMVV ≤200 ml is indeed rather specific for 24-hour SBC, particularly in the setting of concomitant NP, such that a positive nocturnal test for SBC (i.e., a nocturnal-only voiding diary showing all nocturnal voids at or below 200 ml) may reliably rule a diagnosis of SBC based on the 24-hour voiding diary. Further research is needed to corroborate these findings in view of post-void residual volumes which, in summation with voided volumes, more accurately reflect functional bladder capacity.
Concluding message
Nocturnal voided volumes provide valuable insight into voided volumes across the 24-hour period. By definition, a NMVV >200 ml excludes SBC, but a NMVV ≤200 ml may also reliably rule-in a diagnosis of SBC, particularly in patients with comorbid NP. These findings support the use of nocturnal-only voiding diaries in the initial evaluation of nocturia owing to NP.
  1. van Doorn B, Blanker MH, Kok ET, Westers P, Bosch JL. Prevalence, incidence, and resolution of nocturnal polyuria in a longitudinal community-based study in older men: the Krimpen study. Eur Urol 2013;63:542-7.
  2. Presicce F, Puccini F, De Nunzio C, Melchionna A, Lombardo R, Tubaro A. Variations of Nighttime and Daytime Bladder Capacity in Patients with Nocturia: Implication for Diagnosis and Treatment. J Urol. 2019;201(5):962-966.
  3. Hashim H, Blanker MH, Drake MJ, et al. International Continence Society (ICS) report on the terminology for nocturia and nocturnal lower urinary tract function. Neurourol Urodyn. 2019;38(2):499-508.
Funding N/A Clinical Trial No Subjects Human Ethics Committee Veterans Affairs New York Harbor Healthcare Institutional Review Board Helsinki Yes Informed Consent No
07/07/2024 08:57:56