Dysnatremia is a common finding in the intensive care unit (ICU) and may be a predictor for mortality and poor clinical outcomes. Depending on the time of onset (ie, on admission vs later in the ICU stay), the incidence of dysnatremias in critically ill patients ranges from 6.9% to 15%, respectively. The symptoms of sodium derangement and their effect on brain physiology make early recognition and correction paramount in the neurologic ICU. Hyponatremia in brain injured patients can lead to life-threatening conditions such as seizures and may worsen cerebral edema and contribute to alterations in intracranial pressure.