Solute loss plays a major role in polydipsia-related hyponatraemia of both water drinkers and beer drinkers

QJM. 2003 Jun;96(6):421-6. doi: 10.1093/qjmed/hcg078.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Alcohol Drinking / adverse effects
  • Beer
  • Blood Proteins / metabolism
  • Body Weight / physiology
  • Drinking / physiology
  • Female
  • Humans
  • Hyponatremia / physiopathology*
  • Male
  • Middle Aged
  • Prospective Studies


  • Blood Proteins