Introduction: Cerebral salt wasting (CSW) is a potential cause of hyponatremia in the setting of central nervous system (CNS) trauma. CSW is characterized by hyponatremia with elevated urine sodium and hypovolemia. We report a 3-year-old male child with head injury and CSW managed successfully with hypertonic saline infusion. Case report: We present a case of 3-year-old boy who was admitted to the Children's Intensive Care Unit due to vomiting, severe hyponatremia and impaired consciousness. On admission, he is pale, somnolent, sleepy, hypotensive, bradycardic and has muscle cramps. Due to the anamnestic information about head trauma, a magnetic resonance imaging (MRI) of the brain was performed, which was normal with a presence of small arachnoid cyst. In the laboratory findings, urine osmolality and sodium in urine are elevated, along with decreased serum values and decreased serum osmolality. The initial sodium is 117 mmol/L, which is approached by giving hypertonic saline with the continuation of the isotonic solution. The applied measures correct the state of consciousness two hours after arrival and the clinical symptoms of hyponatremia disappear. The boy is discharged home on the sixth day of hospitalisation after endocrinological, neuropediatric and nephrological examination. Conclusion: CSW should always be considered whenever a clinician encounters hyponatremia in patients with cerebral traumas. One can diagnose CSW in hyponatremic patients with decreased volume of extracellular fluid. Increased urinary sodium and urate excretion and high urine osmolality with polyuria support the diagnosis. Mineralocorticoids can be an effective drug in the management of CSW apart from saline infusion.
