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
renal papillary necrosis is caused by ? 
Select and explain. 
A. alcohol, B. cocaine, C. heroin, D. morphine
A: alcohol
Answer: A: alcohol 
Explanation: Etiology # Pyelonephritis # Obstruction of the urinary tract # Sickle cell hemoglobinopathies, including sickle cell trait # Tuberculosis # Cinhosis of the liver, chronic alcoholism # Analgesic abuse # Renal transplant rejection, Radiation, Renal vein thrombosis # Diabetes mellitus # Systemic vasculitis Renal papillary necrosis # Renal papillary necrosis (RPN) is characterized by coagulative necrosis of the renal medullary pyramids and papillae # Renal papillary necrosis generally affects individuals who are in the middle decades of life or older # It is more common in women than in men # 60% of the patients have DM, 30% Urinary tract obsruction, 15% have both. # Renal papillary necrosis is primarily a bilateral process ref : harrisons 21st ed