[Diagnosis and therapy of hyponatremic syndromes]

Hyponatremia is the most common abnormality in electrolyte and water metabolism. In adult patients it is related to high morbidity and mortality. The degree of CNS-damage depends 1st on the absolute serum sodium concentration (NaS) and 2nd on the rapidity with which NaS is lowered. The most frequent etiology of hyponatremia in pediatric patients is dilutional hyponatremia (SIADH, infusion-therapy). Nephrotic syndromes and congestive heart insufficiency associated with cardiac low output are further causes. Being aware of the different pathophysiological mechanism prevention of hyponatremia is easily achieved by monitoring serum electrolytes, water balance and compensating renal factors in critically ill patients. Hyponatremias accompanied by neurological symptoms should be corrected by rapid infusion of hypertonic saline (514 mmol/l). NaS concentration should increase at a rate of 2 mmol/1 hour. Symptoms of central pontine myelinolysis in hyponatremia were not yet described in pediatric patients.