W Musch1, O Xhaet, G Decaux. 1. Department of Internal Medicine, Bracops Hospital, Research Unit for the Study of Hydromineral Metabolism, Erasme University Hospital, Free University of Brussels, Brussels, Belgium.
Abstract
BACKGROUND: Polydipsia-related hyponatraemia is generally considered an acute dilutional state. AIM: To determine whether solute loss plays a role in the pathogenesis of polydipsia-related hyponatraemia. DESIGN: Prospective uncontrolled study. METHODS: We studied routine biochemical volume-related parameters before and after 2 l isotonic saline infusion over 24 h, in 10 consecutive hyponatraemic polydipsia patients (mean age 55 +/- 11 years; 6 beer drinkers and 4 compulsive water drinkers) with initial urinary osmolality <220 mosm/kg H(2)O. In five of these patients, we measured balance data over 24 h. RESULTS: Mean initial plasma protein concentration in the 10 studied polydipsia patients was 7 +/- 0.7 g/dl, unexpectedly high for an acute dilutional state. Mean plasma sodium concentration increased from 126 +/- 5 mmol/l before saline, to 135 +/- 5 mmol/l after infusion of 2 l isotonic saline (p < 0.01). Balance data in five polydipsia patients showed a mean decrease of 1.6 kg of their initial body weight and a mean salt retention of 406 mosm. DISCUSSION: Polydipsia-related hyponatraemia is a mixed disorder, in which about half of sodium decrease is due to solute loss. This explains the apparent paradox of a normal plasma protein concentration, despite the increase in body weight due to water intoxication.
BACKGROUND:Polydipsia-related hyponatraemia is generally considered an acute dilutional state. AIM: To determine whether solute loss plays a role in the pathogenesis of polydipsia-related hyponatraemia. DESIGN: Prospective uncontrolled study. METHODS: We studied routine biochemical volume-related parameters before and after 2 l isotonic saline infusion over 24 h, in 10 consecutive hyponatraemic polydipsiapatients (mean age 55 +/- 11 years; 6 beer drinkers and 4 compulsive water drinkers) with initial urinary osmolality <220 mosm/kg H(2)O. In five of these patients, we measured balance data over 24 h. RESULTS: Mean initial plasma protein concentration in the 10 studied polydipsiapatients was 7 +/- 0.7 g/dl, unexpectedly high for an acute dilutional state. Mean plasma sodium concentration increased from 126 +/- 5 mmol/l before saline, to 135 +/- 5 mmol/l after infusion of 2 l isotonic saline (p < 0.01). Balance data in five polydipsiapatients showed a mean decrease of 1.6 kg of their initial body weight and a mean salt retention of 406 mosm. DISCUSSION: Polydipsia-related hyponatraemia is a mixed disorder, in which about half of sodium decrease is due to solute loss. This explains the apparent paradox of a normal plasma protein concentration, despite the increase in body weight due to water intoxication.
Authors: Nilofar Dorani; Miranda M Zhang; Gopala K Rangan; Lara Abu-Zarour; Ho Ching Lau; Alexandra Munt; Ashley N Chandra; Sayanthooran Saravanabavan; Anna Rangan; Jennifer Q J Zhang; Martin Howell; Annette Ty Wong Journal: BMJ Open Date: 2021-12-09 Impact factor: 2.692