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: Unknown
Chronic Laxative abuse can result in the formation of which type of stone: 
Select and explain. 
A. Xanthine, B. Cysteine, C. Ammonium urate, D. Struvite
C: Ammonium urate
Answer: C: Ammonium urate 
Explanation: Ref. API Textbook of Medicine. Pg. 784
 
Urinary stones due to chronic laxative abuse is due to gastrointestinal loss of fluid and electrolytes leads to chronic depletion of urinary volume ,relative super saturation and many other pathophysiologic derangements .
These calculi are generally radiolucent with uric acid and ammonium urate as major componenent.