This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidney, Subject name: Pediatrics
Least likely cause of renal papillary necrosis? 
Select and explain. 
A. Sickle cell disease, B. Analgesic nephropathy, C. Posterior urethral valves, D. Diabetes with UTI
C: Posterior urethral valves
Answer: C: Posterior urethral valves 
Explanation: c. Posterior urethral valves(Ref: Nelson's 20/e p 2562-2567Ghai 8/e p 485-486)Sickle cell disease, use of analgesics and Diabetes are important causes of Renal papillary necrosis.