Pathogenesis and management of hypernatremia

Abstract

Although the kidney is important in the development of hypernatremia, the primary target organ is the brain. A number of medical conditions are commonly associated with hypernatremia, and these differ substantially among children versus adults. In infants, gastroenteritis with diarrhea is the most common cause, and in older children, mental retardation is often an important contributory factor. In adults, causes of hypernatremia include hyperalimenation, dehydration secondary to either fever or elevated ambient temperature, NaHCO3 administration, and diabetes insipidus. The signs and symptoms of hypernatremia are variable, including seizures and depression of sensorium. Associated metabolic abnormalities include metabolic acidosis, hyperglycemia and weight loss. The mortality of hypernatremia in adults exceeds 40%. Hypernatremia is frequent in subjects with end-stage liver disease and hepatic encephalopathy. Liver transplantation is also associated with a high incidence of hypernatremia and a high mortality, as well as the development of cerebral demyelinating lesions. Histologically, elevation of the plasma sodium by more than 30 mmol/L in less than 24 hours can lead to cellular necrosis, cerebral demyelinating lesions and hypoxic ischemic changes in multiple areas of the brain.