Thomas F Monaghan1, Donald L Bliwise2, Marie-Astrid Denys3, An-Sofie Goessaert3, Veerle Decalf3, Candy Kumps3, Johan Vande Walle4, Jeffrey P Weiss1, Matthew R Epstein5, Jeremy Weedon6, Jason M Lazar7, Karel Everaert3. 1. Department of Urology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA. 2. Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA. 3. Department of Urology, Ghent University Hospital, Ghent, Belgium. 4. Department of Pediatric Nephrology, Ghent University Hospital, Ghent, Belgium. 5. Department of Urology, Temple University Hospital, Philadelphia, PA, USA. 6. Research Division, SUNY Downstate Health Sciences University, Brooklyn, NY, USA. 7. Department of Medicine, Division of Cardiovascular Medicine, SUNY Downstate Health Sciences University, Brooklyn, NY, USA.
Abstract
BACKGROUND: this study compares diuresis rate, sodium clearance and free water clearance (FWC) by age and time of day (nighttime vs. daytime) in subjects with and without nocturnal polyuria (NP) to determine whether these variables affect the phenotype of NP. METHODS: post hoc analysis of two prospective observational studies. Eight urine samples collected at 3-h intervals and a single blood sample were used to calculate daytime (10a/1p/4p/7p/10p) and nighttime (1a/4a/7a) diuresis rates, sodium clearance and FWC. Three mixed linear models were constructed for diuresis rate, sodium clearance and FWC using four predictor variables: NP status (present [nocturnal urine production >90 ml/h] vs. absent [≤90 ml/h]), time of day, age and study identification. RESULTS: subjects with NP experienced higher nighttime versus daytime diuresis rates, sodium clearance and FWC. Regardless of NP status, increased age was accompanied by an increase in the ratio of nighttime/daytime diuresis rate, nighttime sodium clearance and daytime sodium clearance. FWC showed a complex age effect, which was independent of time of day or NP status. CONCLUSIONS: age-related increases in nighttime/daytime diuresis rate, 24-h sodium clearance and 24-h FWC are not specific to subjects with NP. The age-related surge in either nocturnal sodium clearance or nocturnal FWC may represent the relevant substrate for behavioural or pharmacologic interventions targeting sodium diuresis or free water diuresis, respectively. Increases in FWC in older age groups may reflect impaired circadian rhythmicity of endogenous AVP or changes in responsiveness of the aged nephron to water clearance.
BACKGROUND: this study compares diuresis rate, sodium clearance and free water clearance (FWC) by age and time of day (nighttime vs. daytime) in subjects with and without nocturnal polyuria (NP) to determine whether these variables affect the phenotype of NP. METHODS: post hoc analysis of two prospective observational studies. Eight urine samples collected at 3-h intervals and a single blood sample were used to calculate daytime (10a/1p/4p/7p/10p) and nighttime (1a/4a/7a) diuresis rates, sodium clearance and FWC. Three mixed linear models were constructed for diuresis rate, sodium clearance and FWC using four predictor variables: NP status (present [nocturnal urine production >90 ml/h] vs. absent [≤90 ml/h]), time of day, age and study identification. RESULTS: subjects with NP experienced higher nighttime versus daytime diuresis rates, sodium clearance and FWC. Regardless of NP status, increased age was accompanied by an increase in the ratio of nighttime/daytime diuresis rate, nighttime sodium clearance and daytime sodium clearance. FWC showed a complex age effect, which was independent of time of day or NP status. CONCLUSIONS: age-related increases in nighttime/daytime diuresis rate, 24-h sodium clearance and 24-h FWC are not specific to subjects with NP. The age-related surge in either nocturnal sodium clearance or nocturnal FWC may represent the relevant substrate for behavioural or pharmacologic interventions targeting sodium diuresis or free water diuresis, respectively. Increases in FWC in older age groups may reflect impaired circadian rhythmicity of endogenous AVP or changes in responsiveness of the aged nephron to water clearance.
Authors: Kim Pauwaert; An-Sofie Goessaert; Lynn Ghijselings; Thomas F Monaghan; Herman Depypere; Karel Everaert Journal: Int Urogynecol J Date: 2021-01-13 Impact factor: 2.894