This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Medicine
In acute tubular necrosis, all are true except 
Select and explain. 
A. Specific gravity of urine < 1.020, B. Urine Osmolatlity > 500, C. Blood urea: creatinine ratio < 20, D. Urine sodium < 20mmol/l
D: Urine sodium < 20mmol/l
Answer: D: Urine sodium < 20mmol/l 
Explanation: Acute tubular necrosis: - Muddy brown granular or tubular epithelial cell casts- FENa > 1%- UNa > 20 mmol/L- SG < 1.015 Ref: Harrison's 17/e p1757 table 273-2