Could Evening Dietary Protein Intake Play a Role in Nocturnal Polyuria?

Upeksha S Alwis,Lien Dossche,Joris Delanghe,Saskia Roggeman,John Van Camp,Karel Everaert,Johan Vande Walle,Thomas F Monaghan

doi:10.3390/jcm9082532

Upeksha S Alwis, Lien Dossche + Show 6 more

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https://doi.org/10.3390/jcm9082532

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Abstract

Urea is the most abundant and the largest contributing factor for urine osmolality. Urinary urea excretion is highly interrelated with dietary protein intake. Accordingly, an increase of urinary urea excretion due to high protein diet may lead to urea-induced osmotic diuresis. This study aims to explore the association between nocturnal polyuria (NP) and urea. This is a post hoc analysis of a prospective observational study of subjects who completed a renal function profile between October 2011 and February 2015 (n = 170). Each subject underwent a 24 h urine collection, which included 8 urine samples collected at 3 h intervals. Urine volume, osmolality, creatinine, urea and sodium were determined. Urinary urea excretion was used to estimate dietary protein intake. Compared to the control group, subjects with NP exhibited significantly higher nighttime urea and sodium excretion. Estimated evening dietary protein intake was correspondingly significantly higher amongst the NP subgroup. Nighttime diuresis rate was positively associated with age and nighttime free water clearance, creatinine clearance, sodium excretion, and urea excretion in NP subjects. Therefore, increased nocturnal urinary urea excretion may reflect an additional important mediator of nocturia owing to excess nocturnal urine production.

Highlights

Nocturia, or the need to wake up to urinate during the main sleep period, is a highly prevalent and bothersome lower urinary tract symptom [1]
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Higher nighttime urea excretion was observed in the nocturnal polyuria (NP) group

Summary

Introduction

The need to wake up to urinate during the main sleep period, is a highly prevalent and bothersome lower urinary tract symptom [1]. Nocturnal polyuria (NP), or excess urine production during the main sleep period [1], is thought to be the most common cause of nocturia in adults of all ages [3,4]. Recent research has shown that NP is a heterogeneous condition that may be driven by excess free water and/or osmotic diuresis [5], and impaired circadian rhythm in renal handling of free water and sodium has been observed in both adults [6] and children [7] with NP. Current pharmacologic interventions for management of NP involves concomitant medication based on the NP phenotype; such as antidiuretic therapy [6,8]. Lifestyle interventions targeting both nocturnal free water and sodium diuresis have garnered considerable attention in the management of nocturia owing to NP [9,10,11,12]. Relatively less attention has been afforded to urea, which, alongside sodium, is the primary constituent of urine osmolality on molar basis [13]

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