Encephalopathies caused by electrolyte disorders.

Some of the most common reasons for metabolic neurologic disturbances in the setting of a general hospital are frequently encountered electrolyte and related osmolality disorders. Hyperosmolality is usually related to hypernatremia and/or hyperglycemia. Identifying the cause and carefully calculating the water deficit is crucial to appropriate management. Hyponatremia may be hypertonic, isotonic, or hypotonic. When hypotonic, it may be hypervolemic, euvolemic, or hypovolemic in nature. Determining the precise nature of the hyponatremia allows the clinician to focus the therapy appropriately. The rate of development of hyponatremia is crucial to safe and appropriate treatment. In acutely developing hyponatremia, hypertonic saline is required, whereas in slowly developing hyponatremia, water restriction and slow correction is required to avoid the syndrome of osmotic demyelination. Disorders of potassium metabolism are also common electrolyte disorders seen in the general hospital. Appropriate diagnosis and management of hyperkalemia and hypokalemia are also discussed.