Aim To recognise cerebral salt wasting (CSW) in children following central nervous system surgery and differentite it from the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and Diabetes Insipidus (DI).

Methods Two cases admitted to paediatric Intensive care unit following cranial surgery developed cerebral salt wasting and were postoperatively managed.

Cases The first child was a four year old boy admitted to Paediatric Critical Care (PCC) following cranial surgery for a space occupying lesion. On the second postoperative day he developed polyurea (urine output 17 ml/kg/hour). He was noted to have severe hyponatremia with serum sodium 120 mmol/l, low serum osmolality and high urinary sodium content. The second child was a two year old boy who developed lethargy and fever and was diagnosed with E Coli meningitis. He was admitted to PCC following external ventricular drain insertion for a hydrocephalous secondary to meningitis. On the fifth postoperative day, he was noted to be dehydrated with a very high urine output, up to 30 ml/kg/hour. On investigation he was noted to have severe hyponatremia with serum sodium 119 mmol/l, very high urinary sodium content and low serum osmolality. Both children had hyponatremia, high urine sodium concentrations, hypovolemia, and excessive urine output while receiving maintenance fluids. First child required significant sodium supplementation and precise fluid management for 2 weeks and second child for 10 days; eventually normalising with appropriate treatment.

Conclusion These two children showed true Cerebral Salt Wasting following a CNS insult. It is important to diagnose Cerebral Salt Wasting correctly and differentiate it from SIADH and diabetes insipidus. These three conditions cause major disturbances in salt and water metabolism following CNS injury. Incorrect diagnosis and treatment of Cerebral Salt Wasting could increase morbidity significantly.