Hyponatremia.

Hyponatremia is the most common electrolyte disorder in hospitalized patients. Hospital-associated hyponatremia includes community-acquired (e.g., hyponatremia on admission) and hospital-acquired hyponatremia. Acute-onset hyponatremia requires rapid treatment with hypertonic saline to decrease cerebral edema. In cases of chronic hyponatremia (>48 hours), the brain has time to normalize cell volume by losing solutes. However, even mild chronic cases can have adverse outcomes, such as decreased cognition, osteoporosis, increased risk for falls, and fractures. Hyponatremia is associated with increased hospital length of stay, readmissions, morbidity, and mortality. Prompt recognition and appropriate treatment are therefore necessary to improve outcomes.