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: Medicine
Which of the following is NOT a feature of pre renal azotemia? 
Select and explain. 
A. BUN/PCr ratio >20:1, B. Urine sodium (UNa), meq/L <20, C. Urine osmolality, mosmol/L H2O >500, D. Urine/plasma creatinine (UCr/PCr) <20
D: Urine/plasma creatinine (UCr/PCr) <20
Answer: D: Urine/plasma creatinine (UCr/PCr) <20 
Explanation: Urine/plasma creatinine (UCr/PCr) will be > 40 in pre renal azotemia. Difference between pre renal and and acute tubular necrosis: Pre renal failure FENa is less than 1% Urine Na is less than 20mmol/l Urine osmolality is more than 500mosm/kg Fractional excretion of BUN is less than 35% BUN/Creatinine ratio is more than 20:1 Acute tubular necrosis FENa is more than 2% Urine sodium is more than 30 mmol/l Urine osmolarity is less than 350mosm/kg BUN/Creatinine ratio is less than 10:1 Ref: Harrisons principles of internal medicine, 18th edition, Page 337