This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidney Stones & Renal Tubular Acidosis, Subject name: Medicine
All are indicated in a 30-year-old patient with increased serum cystine and multiple renal stones except: 
Select and explain. 
A. Cysteamine, B. Increase fluid intake, C. Alkalinization of urine, D. Penicillamine
A: Cysteamine
Answer: A: Cysteamine 
Explanation: The clinical diagnosis of profile given in the question is CYSTINURIA . Cystinuria- AR,defect in re-absorptive transpo of cystine and the dibasic amino acids ornithine, arginine, and lysine from the luminal fluid of the renal proximal tubule and small intestine. Urinalysis- hexagonal shaped crystals: pathognomonic of cystinuria. The foundation of cystine stone prevention is adequate hydration and urinary alkalinization. When this conservative therapy fails, the addition of drugs, such as D-penicillamine and captopril. -The clinical profile should not be confused with Cystinosis which is treated with Cysteamine.