This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Inflammatory bowel disease, Subject name: Surgery
Type of renal stone formed in a patient with regional enteritis: 
Select and explain. 
A. Calcium oxalate, B. cysteine, C. Struvite, D. Urate
A: Calcium oxalate
Answer: A: Calcium oxalate 
Explanation: Calcium oxalate stone is formed in patient with Regional enteritis Regional enteritis causes decreased Bile salt absorption, thus Ca++ sequestration and increased absorption of Oxalate