A Systematic Approach to the Hyponatremic Patient

∑ Hyponatremia is the most common electrolyte disorder.Sometimes it is not easy to consider the differential diagnosis and to establish a final diagnosis.Hyponatremia is acute severe (less than 115 mmol/L) when lasting for 36 to 48 hours.This condition is a medical emergency because these patients have pronounced symptoms as the result of brain edema.It should be rapidly corrected to approximately 130 mmol/L to prevent permanent brain damage.In chronic severe hyponatremia, the symptoms are mild and there is no brain edema.Many authors recommend correction to approximately 130 mmol/L at a rate of less than 0.5 mmol/h, to minimize the risk of cerebral myelinolysis.In the near future, vasopressin antagonists will become available.Preliminary experience has already demonstrated their efficacy in inducing sustained water diuresis and correction of hyponatremia.