Cystinuria

Excerpt

Cystine stones account for only about 1% to 2% of all kidney stones but represent roughly 6% to 8% of all pediatric calculi. Eighty percent of cystinuria patients will have their first stone during their first two decades of life.

The name "cystine" comes from its original description as "bladder calculi" in 1833.

Kidney stones are the singular clinical manifestation of this condition. The primary treatment is the optimization of urinary volume and pH with hydration and oral alkalinizing medications. Second-line medical therapy consists of thiol-based drugs and is used in patients where conservative measures alone are insufficient.

While most cystine stone formers will make pure cystine stones, up to 40% may develop mixed calculi also containing calcium oxalate, calcium phosphate, or struvite.

Compared to calcium stone formers, cystine nephrolithiasis patients will tend to make larger stones, require more urological procedures, make stones more often, and start at an earlier age. They also face a greater risk of eventual kidney damage and chronic renal failure compared to calcium nephrolithiasis patients. Cystinuria patients also report relatively poor health-related quality of life scores due to multiple recurrent stone episodes and related surgical procedures although these scores can be improved with optimized prophylactic therapy.