C MANNIX1,2, A RANGAN3, J ZHANG1,2,G RANGAN1,2, AT WONG1,2
1Centre for Transplant and Renal Research, Westmead Institute for Medical Research, University of Sydney, Westmead, Australia, 2Department of Renal Medicine, Westmead Hospital, Westmead, Australia, 3Nutrition and Dietetics, School of Life and Environmental Science, University of Sydney, Sydney, Australia
Aim: To determine the influence of season on fluid intake in patients with autosomal dominant polycystic kidney disease (ADPKD).
Background: Adequate hydration has been hypothesised to reduce the progression of ADPKD. Multiple factors influence fluid intake behaviour and specifically the role of seasonal variations in patients with ADPKD are not known.
Methods: The mean baseline daily fluid intake was assessed in patients with ADPKD (18-65 years old; eGFR≥30ml/min/1.73m²; n=100 and living primarily in Sydney and Perth) who were screened for the PREVENT-ADPKD study (a randomised controlled trial to determine if adequate hydration will slow kidney growth in ADPKD). Fluid intake was assessed using a beverage frequency questionnaire (BFQ) (previously validated for this purpose in this population), 24-hour urine volume, osmolality and other serum markers of hydration. One-way ANOVA was used to analyse inter-group differences.
Results: Fifty-three percent of the cohort were male with a mean age of 43±11 years old and BMI 27±5kg/m². The mean daily fluid intake in summer (n=20, 3040±930ml), autumn (n=28, 2843±1076ml), winter (n=18, 2822±1138ml) and spring (n=34, 2715±1027ml) were similar and the inter-seasonal differences were not significant (P=0.748). Similarly, 24-hour urine volume did not vary by season (P=0.221), nor did 24-hour urinary osmolality and sodium, or serum sodium and osmolality.
Conclusion: Fluid intake was stable through the year with no increase during the warmer months. These baseline data suggest that additional coaching during summer may be warranted in patients who are randomised to the prescribed fluid intake group (the intervention) in the PREVENT-ADPKD study. The limitations of this data are the sample size and that further studies are needed to determine if seasonal variations in intra-individual fluid intake exist.
Carly Mannix is a Senior Research Dietitian and PhD candidate at the Westmead Institute for Medical Research (Westmead Hospital and University of Sydney). She is presently undertaking the PREVENT-ADPKD study which is a national multicentre randomised controlled trial that is investigating the role of hydration on slowing the progression of autosomal dominant polycystic kidney disease, and this is the subject of her PhD thesis. She is an Accredited Practising Dietitian with the Dietitians Association of Australia. She holds a Master of Nutrition and Dietetics (2016) and Bachelor of Applied Science (Exercise and Sport Science) (2014) from the University of Sydney.