<prompt> In acute tubular necrosis, all are true exceptSpecific gravity of urine 1.020Urine Osmolatlity 500Blood urea: creatinine ratio 20Urine sodium 20mmoll  <response>: Acute tubular necrosis: - Muddy brown granular or tubular epithelial cell casts- FENa 1- UNa 20 mmolL- SG 1.015 Ref: Harrisons 17e p1757 table 273-2 