Can a Child with Dengue Encephalitis Develop Hypernatremia?
No, hypernatremia is not a typical feature of dengue encephalitis in children; hyponatremia is the characteristic electrolyte abnormality associated with dengue infections, including dengue encephalitis. 1, 2, 3
Electrolyte Patterns in Dengue Infections
Hyponatremia is the Expected Finding
Hyponatremia occurs 9.7 times more commonly in dengue patients compared to non-dengue patients, with mean serum sodium levels significantly lower in children with dengue infections 2
Low plasma sodium is found in approximately 60% of patients with viral encephalitis, and hyponatremia is specifically noted as a clinical feature that may suggest antibody-mediated or viral encephalitis 1
In dengue encephalitis specifically, hyponatremia is recognized as one of the metabolic complications that can contribute to encephalopathy, along with cerebral edema, hypoperfusion, liver failure, and renal failure 3, 4
Mechanism of Hyponatremia in Dengue
Dengue patients demonstrate significantly lower urine sodium levels (< 20 mEq/L), indicating circulatory volume depletion and appropriate renal sodium conservation, which is 8.1 times more common in dengue patients 2
The syndrome of inappropriate antidiuresis (SIAD) can occur with CNS infections including viral encephalitis, leading to water retention and subsequent hyponatremia 1
Dengue shock syndrome patients show even more pronounced hyponatremia, with mean serum sodium levels significantly lower in shock patients compared to non-shock dengue patients 2
Clinical Implications
If Hypernatremia is Present
Hypernatremia in a child with suspected dengue encephalitis should prompt consideration of alternative or additional diagnoses, as this would be atypical for dengue infection 2, 3
Iatrogenic hypernatremia could develop from inappropriate fluid management, particularly if isotonic or hypertonic fluids are administered excessively during resuscitation 5
Hypernatremia may indicate inadequate water intake or excessive water losses from other causes unrelated to the dengue infection itself 1, 5
Management Considerations
Monitor serum sodium levels closely in children with dengue encephalitis, as hyponatremia is the expected electrolyte disturbance and requires appropriate fluid management 1, 2
Avoid using normal saline (0.9% NaCl) as the primary maintenance fluid in dengue patients, as this can worsen electrolyte imbalances and increase fluid overload risk 1
If hypernatremia develops, use hypotonic fluids (5% dextrose in water) for correction, with a target reduction rate of 10-15 mmol/L per 24 hours to prevent cerebral edema 1, 5
Common Pitfalls
Do not assume all electrolyte abnormalities in febrile encephalitis are the same—dengue has a characteristic pattern of hyponatremia that distinguishes it from other causes 2, 3
Hypernatremia in dengue encephalitis should raise suspicion for iatrogenic causes from aggressive fluid resuscitation with isotonic fluids or inadequate free water provision 5
The presence of hypernatremia does not rule out dengue, but it is not a typical feature and warrants investigation for other contributing factors or complications 2