[Hyponatremia: basic concepts and practical approach].

Hyponatremia is the most common electrolyte imbalance in hospitalized patients. It is associated with several unfavorable endpoints such as: the need for intensive care, longer hospital stay, higher hospitalization costs, discharge to long-term care facilities, and mortality. It is still not clear if there is a direct causal relationship or if hyponatremia is simply a marker of disease severity. Nevertheless, it is quite clear that improper management of a hyponatremic patient may result in severe neurologic damage or death. This paper addresses the basic pathophysiologic concepts about hyponatremia followed by a practical approach to its diagnosis and management.