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
[{'content': 'True about pre-renal azotemia \nSelect and explain. \nA. "Muddy brown" granular casts, B. Urine creatinine / plasma creatinine > 20, C. FeNa <1, D. Urine osmolality >500 mOsm/kg', 'role': 'user'}, {'content': 'Answer: A \nExplanation: In pre-renal azotemiaBUN/creatinine ratio above 20, FeNa<1%, hyaline casts in urine sediment,urine specific gravity >1.018, urine osmolality >500 mOsm/kgPigmented "muddy brown" granular casts and tubular epithelial cell casts are seen in acute tubular necrosis.Ref: Harrison\'s 19e pg: 1805', 'role': 'assistant'}]