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: Medicine
Which investigation should be avoided in a proven case of renal papillary necrosis - 
Select and explain. 
A. Urine acidification test, B. Sickling test, C. TB-PCR-urine, D. Bacterial culture ofurine
A: Urine acidification test
Answer: A: Urine acidification test 
Explanation: Urinary acidification ability may be evaluated by an acidification test or maximum urinary pCO2 assessment with alkaline urine. The maximum urinary pCO2 test using acetazolamide and sodium bicarbonate is an easy test to confirm the lack of urine acidification in distal renal tubular acidosis in children Ref Harrison20th edition pg 234