Login to Access Video or Poster Abstract: MP90-10
Sources of Funding: NIH NIDDK K12-DK-07-006: Multidisciplinary K12 Urologic Research Career Development Program (TC)_x000D_

Introduction

Cystinuria is a rare systemic genetic disease caused by a defect in an amino acid transporter which results in elevated urinary cystine excretion and severe recurrent stone disease. Interestingly, a subset of patients consistently forms stones unilaterally, despite no evidence of anatomic differences between their two kidneys. This study aimed to determine if bilateral cystine stone formers had different clinical outcomes compared to unilateral stone formers and whether thiola use impacted these outcomes. _x000D_

Methods

This was a retrospective case-control study for all cystine stone patients evaluated and treated at the University of California, San Francisco between 1994 and 2015. The presence of unilateral (only formed stones in one kidney alone during their entire lifetime) versus bilateral (formed stones in both kidneys at some point in their lifetime) stone disease was determined with review of all imaging studies, radiology reports, and clinic notes. Demographic data, clinical presentation, current medical treatment and overall renal function were compared between the two groups. _x000D_

Results

42 cystine stone patients were identified and included in the analysis. Mean age at first presentation was 21.7±14.0 years (mean current age 44.2±19.7 years) with women representing 52.4% of all cases. Most patients presented with flank pain (62.1%) following by recently passed stone (24.1%). Of the 42 patients, 28 patients (66.7%) had bilateral stone disease, while 9 patients (21.4%) only experienced left sided stones, and 5 patients (11.9%) right side stones. _x000D_ _x000D_ Bilateral stone formation did not correlate to gender (p = 0.38), age of first presentation (p = 0.89), or family history of stone disease (p = 0.32). Thiola was used by 21.4% of patients with unilateral disease and 35.7% of patients with bilateral disease (p = 0.32). Bilateral cystine stone formation was significantly associated with a higher number of lifetime stone surgeries (7.5 versus 3.7 sessions, p <0.05). Despite this increased number of surgeries for patients with bilateral disease, thiola use and current serum creatinine level (1.05 versus 0.94 mg/dL, p = 0.38) were not significantly different between the two groups. _x000D_

Conclusions

The majority of cystinuric patients will form stones bilaterally during their lifetime, and require more surgical interventions than those who only form cystine stone on one side. Despite this, overall renal function (via serum creatinine level) is still well preserved in bilateral and unilateral cystine stone formers and thiola use may not impact laterality or severity of disease. _x000D_

Funding

NIH NIDDK K12-DK-07-006: Multidisciplinary K12 Urologic Research Career Development Program (TC)_x000D_