This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Plasma urea / creatinine ratio of 20:1 may be seen in : 
Select and explain. 
A. Rhabdomyolysis, B. Ureteric calculi, C. Pre-renal failure, D. Chronic Glomerulonephritis
C: Pre-renal failure
Answer: C: Pre-renal failure 
Explanation: Answer is c (Pre-renal failure) Plasmaurea / creatinine ratio of 20:1 is characteristic of prerenal ARF Rhabdomyolysis and chronic glomerulonephritis are causes of Intrinsic ARF and are associated with a plasma urea / creatinine ratio of < 10-15. Ureteric calculi are associated with post-renal ARF