What dietary factors can induce hyponatremia?

Updated: Jun 17, 2019
  • Author: Eric E Simon, MD; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

Severe malnutrition seen in weight-conscious women (low protein, high water intake diet) is a special condition in which a markedly decreased intake of solutes occurs, which limits the ability of the kidney to handle the free water. Because a mandatory solute loss of 50-100 mOsm/kg of urine exists, free water intake in excess of solute needs can produce hyponatremia. [24] Another example is beer drinker's potomania, because a diet consisting primarily of beer is rich in free water but solute poor.

Compulsive intake of large amounts of free water exceeding the diluting capacity of the kidneys (>20 L/d), even with a normal solute intake of 600-900 mOsm/d, may also result in hyponatremia, but in contrast to SIADH, the urine is maximally dilute. In addition to a central defect in thirst regulation, which plays an important role in the pathogenesis of primary polydipsia, different abnormalities in ADH regulation have been identified in psychotic patients, all impairing free water excretion. Transient stimulation of ADH release during acute psychotic episodes, an increase in the net renal response to ADH, downward resetting of the osmostat, and antipsychotic medication may contribute. Limiting water intake will rapidly raise the plasma sodium concentration as the excess water is readily excreted in dilute urine [25]


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