Hypernatremia in children

Abstract

Hypernatremia results from a deficit of total body water in relation to the total body's sodium stores. This is caused by two main mechanisms: 1) net water depletion exceeding sodium losses or 2) increased sodium gain exceeding water gain. Net water depletion occurs when increased water loss exceeds sodium loss, either due to extrarenal losses (increased evaporative water losses, hypernatremic dehydration caused by diarrhea) or to renal losses (central and nephrogenic diabetes insipidus, intrinsic renal disease). Insufficient water intake occurs with neonatal hypernatremic dehydration secondary to lactation failure, essential hypernatremia or osmoreceptor dysfunction. Increased sodium gain can be caused by iatrogenic hypernatremia, administration of concentrated infant formula, deliberate abusive water restriction and deliberate or non-accidental salt poisoning. Hypernatremia results in a movement of water across cell membranes from the intracellular to the extracellular space, resulting in cellular dehydration, which, in cells of the central nervous system results in brain shrinkage leading to tearing of cerebral blood vessels and neurological complications. As a protective mechanism, idiogenic osmoles accumulate inside the brain cells to help them retain water intracellularly. However this may lead to cerebral edema during rapid rehydration as these idiogenic osmoles attract water inside the neurons. As the appropriate management of hypernatremia invariably depends on the underlying mechanism and cause, a methodical history taking and clinical examination, with the judicious use of laboratory tests will lead to a precise etiological diagnosis to enable appropriate and timely therapy.

The frequency of hypernatremia at presenting to the Emergency Department with acute bronchiolitis

“…Hypernatremia is defined as serum sodium (Na) concentration higher than 145 meq/ L [1]. It shows net water loss or excess sodium intake in the body.…”

“…If water is available, it is possible to prevent hypernatremia by taking in water. However, in cases of inability to ask for water, such as infants, intubated patients, or patients with neurological deficits, hypernatremia will occur due to insufficient water intake [1][2][3].…”

“…However, we suspect that (I) an increase in extrarenal fluid loss in acute bronchiolitis symptoms, (II) immaturity of renal functions about the capacity to excrete excess sodium in infants, and (III) infancy inability to describe thirst, may predispose to hypernatremia in young children with acute bronchiolitis [1,3,4,9]. Since hypernatremia increases the risk of morbidity and mortality even at mild levels, it is important to recognize it in the early period and apply the essential treatment [3,10].…”