[Hyponatremia in the light of the most recent guidelines - diagnostics and differential diagnosis]

Hyponatremia is still considered as a challenge of today's medicine. It is an independent factor responsible for the increased mortality among hyponatremic population and its clinical expression might be made up of threatening neurological symptoms, e.g. brain oedema. Moreover, inappropriate treatment of hyponatremia may be followed with grievous consequences in the form of osmotic demyelination syndrome. Hyponatremia could also arise from iatrogenic origins. Thus, education concerning issues related to hyponatremia as the most frequent, though often underestimated, waterelectrolyte imbalance seems to be fundamental. This paper is a review of the current state of knowledge about hyponatremia with regard to its causes, diagnostics and differential diagnosis based on the prevailing guidelines elaborated by American and European experts independently.