<prompt> A patient following head injury was admitted in intensive care ward with signs of raised intracranial pressure. He was put on ventilator and ataed on intravenous fluids and diuretics. Twenty four hours later his urine output was 3.5 litres, serum sodium 156 mEql and urine osmolality of 316 mOsmkg. The most likely diagnosis based on these parameters isHigh output due to diureticsDiabetes insipidusToo much infusion of normal salineCerebral salt retaining syndrome  <response>: Answer is A High output due to diuretics: Presence of high urine osmolality 300 316 mosmolKg along with increased serum Na suggest a diagnosis of solute diuresis. The patient inquestion has sustained head injury and mannitol is often used insuch cases to reduce the intracranial pressure. Solute diuresis secondary to use of mannitol diuretic explains the parameters of the patient in question. 