What causes cystine stones in nephrolithiasis?

Updated: Jun 21, 2018
  • Author: Chirag N Dave, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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Answer

Cystine stones account for 2% of renal calculi. They arise because of an intrinsic metabolic defect resulting in failure of renal tubular reabsorption of cystine, ornithine, lysine, and arginine. Urine becomes supersaturated with cystine, with resultant crystal deposition.

Cystine stones are treated with a low-methionine diet (unpleasant), binders such as penicillamine or a-mercaptopropionylglycine, large urinary volumes, or alkalinizing agents. A 24-hour quantitative urinary cystine determination helps to titrate the dose of drug therapy to achieve a urinary cystine concentration of less than 300 mg/L.


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