RESUMO
Sodium is the most important osmotically effective cation in the extracellular space and very important for the water balance of the organism. Disturbances in the sodium homeostasis are therefore usually closely associated with disturbances in the water balance. The most important organs involved in the regulation of the sodium homeostasis are the kidneys and the brain. Disturbances of sodium homeostasis are common electrolyte disturbances, which can cause serious complications, as well as their improper therapy. The aim of this article is to inform about the etiology of disturbances of sodium homeostasis and to present important therapeutic principles.The TUR syndrome is a complication that can occur in the context of transurethral resection of the prostate which can lead to the inundation of larger amounts of hypotonic, electrolyte-free rinsing solution into the circulation and severe hyponatremia. Central pontine myelinolysis is a dangerous complication of a too fast compensation of hyponatremia. Exercise-associated hyponatremia (EHA) is a severe complication due to an inappropriately high intake of hypotonic fluids (mineral water, "isotonic sports drinks") during endurance sports. Due to the increasing popularity of endurance sports competitions (marathon, triathlon), an increasing incidence of this potentially life-threatening electrolyte disorder is to be expected.
