A MUNT 1,3, N DORANI 1,2, M ZHANG 1,2, L ABU-ZAROUR 1,2, R LAU 1,2, S SARAVANABAVAN1,3, A RANGAN2, M HOWELL4, A WONG1,3, G RANGAN1,3
1Centre for Transplant and Renal Research, Westmead Institute For Medical Research, The University of Sydney, Westmead, Australia, 2Nutrition and Dietetics, School of Life and Environmental Sciences, The University of Sydney, Camperdown, Australia, 3Department of Renal Medicine, Westmead Hospital, Westmead, Australia, 4School of Public Health, University of Sydney, Camperdown, Australia
Aim: To determine the clinical characteristics and outcomes of hyponatraemia associated with excess water intake.
Background: Increasing water intake is rarely associated with life-threatening hyponatremia. We performed a systematic review to define clinical characteristics of hyponatraemia associated with excess water intake.
Methods: This review was conducted using PRISMA guidelines. Studies investigating the relationship between oral water intake and hyponatraemia in adults were included (1946-2019). Studies reporting non-oral routes of water administration; non-water induced hyponatraemia; children or animals and/or if serum sodium values absent were excluded.
Results: A total of 2,970 articles were identified and 177 were included for review (n=590 patients). The average age was 45.8+16.1 years, 47% female, 60% had chronic psychiatric conditions and 34% were healthy. The median volume of water consumed and serum sodium at presentation was 8L/day (IQR: 6-13L/d), and 118 mmol/L (IQR:111-123 mmol/L), respectively. Forty-one percent presented with symptoms within 48 hours, and the motivator for increased water intake was psychogenic polydipsia (62%); adhering to iatrogenic advice (16%) and replacing losses from exercise (12%). Most patients (68%) made a complete recovery, but mortality was 13% and symptoms persisted in 11%. The serum sodium was lower in psychiatric patients (115 mmol/L) compared to healthy adults (122 mmol/L;P<0.0001), despite similar volumes of water intake (P=0.36). Compared to healthy adults, psychogenic polydipsia was the main reason for excess water intake in psychiatric patients (71% vs. 26%) whereas exercise as a reason was less prevalent (31% vs. 69%) (P<0.001).
Conclusion: These data suggest severe hyponatraemia requires daily water intake to substantially exceed population-based recommendations. Patients with underlying chronic psychiatric disorders may have a physiological predisposition for developing this complication and should be monitored closely.
Alexandra Munt is an Accredited Practising Dietitian working in Polycystic Kidney Disease research at the Westmead Institute for Medical Research.