Hypernatremia

Hypernatremia is defined as a serum sodium concentration > 145 mmol/L. Hypernatremia is unlikely to be the cause of AMS until the sodium concentration is > 155 mEq/L.

Hypernatremia generally occurs in infants, the debilitated, and the elderly; that is, generally in those who do not control their own dietary intake. Even a slight increase in serum sodium levels (3 mEq/L) above baseline triggers an intense thirst response in patients with normal physical abilities, mentation, and an intact thirst mechanism. This triggers water intake and a correction of the serum sodium before significant hypernatremia ensues.

Hypernatremia is usually precipitated by an illness that increases water loss, or, less commonly, by excessive sodium intake. Diarrhea accounts for the majority of cases in young children (40% to 90%). Other precipitants in pediatric patients include pneumonia (10%), urinary tract infections, various CNS diseases, and inadequately diluted infant formulas. Complications include intracranial hemorrhages and arterial thrombosis. Permanent brain damage affects 10% to 15% of survivors.

Half of elderly patients with hypernatremia live in nursing homes. Hypernatremia is frequently precipitated by infection (pneumonia, 39%; urinary tract infections or urosepsis, 28%; bacteremia, 17%). In adults, co-morbidities result in a higher mortality (40% to 60%) and incidence of permanent neurologic sequelae (38%).

Undiagnosed diabetes insipidus (DI) is a rare cause of hypernatremia in the ED but should be considered in patients who have recently undergone intracranial surgery. Persistently high urine output with concomitant volume depletion is a clue to this diagnosis.

Causes

Hypernatremia is high sodium in the blood that occurs with excessive fluid loss. When fluid is lost and not replaced, sodium is not adequately excreted from the body. The causes such as including, Diabetes insipidus, Diuretic medication, Excessive vomiting, Severe burn, Diarrhea, Sweating, Excessive salt intake and Heavy exercise, exertion. Hypovolemic, hypernatremia is include some importent cuses eg. Excessive perspiration, Renal dysplasia, Obstructive uropathy and Osmotic diuresis.

Symptoms

• AMS +++++, with severe hypernatremia causing lethargy to coma. Infants may be irritable and have a high-pitched cry.
• Infants are more likely to have seizures +++ to ++++, depending on severity of hypernatremia and rapidity of rise, than adults ++
• Anorexia (infants: decreased feeding), nausea, and vomiting
• Oliguria ++++
• Symptoms stemming from the precipitating illness may predominate; diarrhea (90%) in infants, infection in any age group.

Signs

• AMS: lethargy to coma
• The features of volume depletion (weak pulses, and poor capillary perfusion) may be absent until late in the course.
• A doughy consistency of the skin is common.

Treatment

Hypernatremia is treated by replacing water. In all but the mildest cases, dilute fluids are given intravenously. The sodium level in the blood is reduced very slowly, because correcting the condition too rapidly can cause permanent brain damage. In emergencies, such as when hypernatremia is causing neurological symptoms, infusions may be conducted with salt solutions containing 0.45% sodium chloride, which is half the normal physiologic level.

Some drugs used to treat electrolyte imbalance may be unsafe for pregnant women and should not be taken before consulting a physician.