This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Child presents after trauma to head with hyponatremia, volume depletion and increased excretion of urinary Na . What is the probable diagnosis? 
Select and explain. 
A. Cerebral salt wasting syndrome, B. SIADH, C. Adrenal hemorrhage, D. Autonomic failure
A: Cerebral salt wasting syndrome
Answer: A: Cerebral salt wasting syndrome 
Explanation: Answer- A. Cerebral salt wasting syndromeElectrolyte imbalance is common in traumatic brain injury (TBI), and contributes to brain swelling and to causing seizures.Cerebral salt wasting, a poorly understood form of excretory dysregulation in association with brain insult, leads to volume depletion and hlponatraemia.