This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Chronic Kidney Disease and Uremia, Subject name: Medicine
[{'content': 'Fractional excretion of sodium < 1 is seen in \nSelect and explain. \nA. Pre renal azotemia, B. Acute tubular necrosis, C. Acute ureteral obstruction, D. Interstitial nephritis', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Pre renal azotemia * Urine Diagnostic Indices in differentiation of prerenal Vs Intrinsic Renal FailureDiagnostic IndexPrerenalARFIntrinsic Renal ARF* Fractional Excretion of Na<1> 1* Urine Sodium Concentration (mmol/L)<10>20* Urine Creatinine to Plasma Creatinine ratio>40<20* Urine osmolality (mosmol/kgH20)>500~ 300* Renal failure Index<1>1* Urine urea Nitrogen to plasma urea Nitrogen>8<3* Plasma BUN/Creatinine Ratio>20< 10-15* Urinary SedimentHyalineCastsMuddy Brown Granular Cast* Urine Specific gravity> 1.020-1.010o Acute tubular necrosis is a cause of intrinsic ARF.", 'role': 'assistant'}]