Endocrine Abstracts

JOINT2458

Introduction: Electrolyte disorders are common in central nervous system (CNS) diseases, including subarachnoid hemorrhage, traumatic brain injury, cerebral tumors, infections and postoperative neurosurgical setting. These conditions can be associated with both the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and to cerebral salt wasting (CSW). Hypothalamic-neurohypophyseal system affections instead, can lead to central diabetes insipidus (CDI). CSW is characterized by hyponatremia and hypovolemia due to excessive sodium loss in urine. SIADH presents as euvolemic hyponatremia due to inappropriate ADH secretion. CDI is primarily characterized by polyuria due to insufficient ADH. The table below summarizes the key differences among these syndromes to avoid misdiagnosis and inappropriate therapy. We present a case of a child with chiasmatic-hypothalamic tumor who developed post-surgery fluid and electrolyte imbalance, detailing the initial neurosurgical and intensive care approach and subsequent endocrine management.

Case presentation: A 3-years-old girl with chiasmatic-hypothalamic astrocytoma underwent lesion debulking surgery. Intraoperatively and postoperatively, she presented polyuria (5 mL/kg/h) with normal natremia. Desmopressin and sodium chloride infusion were administered. The next day she developed hyponatremia (Na 130 mEq/l)with persistent polyuria, prompting a second desmopressin bolus. On postoperative day two, diuresis increased (10 mL/kg/h) and laboratory tests showed: Na 125 mEq/l, K 3.2 mEq/l, urinary Na 164 mEq/L. Suspecting CSW, endocrinologist specialist recommended stopping desmopressin, initiating hypertonic saline and administering fludrocortisone (0.05 mg twice daily). Strict fluid balance monitoring and electrolyte surveillance were emphasized. Hypokalemia, likely due to mineralocorticoid therapy, was corrected with potassium infusion. As fluid and electrolytes stabilized, sodium and potassium supplementation were gradually discontinued, and fludrocortisone was reduced.

Discussion: Accurate determination of the patient’s volume status is the key to diagnose CSW and to differentiate from SIADH, while natremia and urine concentration can help to rule out CDI. Hyponatremia in CSW must be corrected gradually to prevent osmotic demyelination. Fludrocortisone therapy may induce hypokalemia, requiring frequent monitoring of sodium and potassium levels. Proper diagnosis and management are key to avoid complications.