From the Guidelines
Hypernatremia is often caused by iatrogenic factors, particularly in very low birth weight infants (VLBWI), resulting from incorrect replacement of transepidermal water loss, inadequate water intake, or excessive sodium intake. According to the espghan/espen/espr/cspen guidelines on pediatric parenteral nutrition 1, hypernatremia can be attributed to various factors, including:
- Incorrect replacement of transepidermal water loss (TEWL)
- Inadequate water intake
- Excessive sodium intake, which can be inadvertent during the transition phase These factors can lead to an imbalance in the infant's intravascular volume and hydration status, ultimately resulting in hypernatremia. It is essential to assess the infant's hydration status and intravascular volume to determine the underlying cause and guide therapeutic measures 1. Furthermore, it is crucial to avoid rapid correction of hypernatremia, as this can induce cerebral edema, seizures, and neurological injury, and instead aim for a reduction rate of 10-15 mmol/L/24h 1.
From the Research
Hypernatremia Causes and Effects
- Hypernatremia reflects a net water loss or a hypertonic sodium gain, with inevitable hyperosmolality 2
- It can be caused by a lack of free water or an increased salt load 3
- Out-of-hospital acquired hypernatremia is often caused by an increased loss of water or a decreased water intake, while hospital-acquired hypernatremia is often induced by an inadequate fluid balance with saline infusions, saline overload, or due to osmotic diuresis 3
- Essential hypernatremia is a rare condition with unclear pathogenesis, and it can be associated with partial central diabetes insipidus and adypsia 4
Symptoms and Complications
- Non-specific symptoms such as anorexia, muscle weakness, restlessness, nausea, and vomiting tend to occur early 2
- More serious signs follow, with altered mental status, lethargy, irritability, stupor, and coma 2
- Acute brain shrinkage can induce vascular rupture, with cerebral bleeding and subarachnoid hemorrhage 2
- Cerebral edema can result if hypernatremia is corrected too rapidly, as the relatively more hypertonic intracellular fluid accumulates water 2, 3
- Chronic hypernatremia affects all cell functions predominantly with cerebral symptoms and coma; the main complication is a too-rapid compensation of an adapted electrolyte imbalance with development of cerebral edema 3
Treatment and Management
- Desmopressin acetate can be an effective treatment for essential hypernatremia, especially in cases associated with partial central diabetes insipidus and adypsia 4
- Patients with cranial diabetes insipidus treated with desmopressin are at risk of developing both hypernatraemia and hyponatraemia, and require close monitoring and management 5
- The rate of correction of hypernatremia should not exceed 12 mEq/liter/day to avoid cerebral edema 2