This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Renal physiology, Subject name: Physiology
[{'content': 'Which of the following renal alterations would most likely preserve the GFR? \nSelect and explain. \nA. Defect in the elimination of hydrogen ions in the distal tubule, B. Luminal obstruction by renal tubular casts, C. Increased interstitial pressure, D. Decreased intrarenal nitric oxide', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The renal alteration that would most likely preserve the GRF is type I distal renal tubular acidosis, in which hydrogen ions diffuse back into the distal tubule. This not only retains hydrogen ions, but also reduces the distal tubule reabsorption of bicarbonate. The other choices listed are assocated with acute tubular necrosis and decrease the GFR.', 'role': 'assistant'}]