Hypernatremi

Hypernatremia, or hypernatemi in some languages, is an elevated serum sodium concentration, typically defined as a plasma sodium level above 145 mmol/L. It reflects a net free water deficit relative to sodium and creates extracellular hyperosmolality, which draws water from cells and can particularly affect brain cells. The condition can be acute or chronic, and its presentation depends on the rate of onset and the underlying cause.

Causes of hypernatremia fall into water loss and sodium gain. Water loss occurs with inadequate water intake, reduced thirst, fever, sweating, diarrhea, or osmotic diuresis (for example from uncontrolled diabetes mellitus or certain medications). Sodium gain is less common and may result from administration of hypertonic saline, concentrated salt solutions, or substantial salt intake. Diabetes insipidus (central or nephrogenic) is an important etiologic category due to free water loss.

Clinical features include thirst, dry mucous membranes, tachycardia, and hypotension; neurologic symptoms range from restlessness and confusion to seizures or coma in severe cases.

Diagnosis rests on measuring serum sodium and assessing volume status, with additional tests such as plasma osmolality, urine osmolality, and urine sodium to distinguish etiologies (eg, diabetes insipidus vs osmotic diuresis) and to guide management.

Management focuses on correcting the free water deficit while addressing the underlying cause. If hypovolemia is present, start with isotonic saline; after stabilization, use hypotonic fluids to replace free water deficits. Correct sodium gradually to avoid cerebral edema or osmotic demyelination, typically not more than about 10–12 mEq/L per 24 hours for chronic hypernatremia. Monitor serum sodium and fluid status closely; treat diabetes insipidus if present (eg, with desmopressin) and address factors contributing to water loss or sodium gain.