Skip to main content
Journal cover image

Do Urinary Cystine Parameters Predict Clinical Stone Activity?

Publication ,  Journal Article
Friedlander, JI; Antonelli, JA; Canvasser, NE; Morgan, MSC; Mollengarden, D; Best, S; Pearle, MS
Published in: J Urol
February 2018

PURPOSE: An accurate urinary predictor of stone recurrence would be clinically advantageous for patients with cystinuria. A proprietary assay (Litholink, Chicago, Illinois) measures cystine capacity as a potentially more reliable estimate of stone forming propensity. The recommended capacity level to prevent stone formation, which is greater than 150 mg/l, has not been directly correlated with clinical stone activity. We investigated the relationship between urinary cystine parameters and clinical stone activity. MATERIALS AND METHODS: We prospectively followed 48 patients with cystinuria using 24-hour urine collections and serial imaging, and recorded stone activity. We compared cystine urinary parameters at times of stone activity with those obtained during periods of stone quiescence. We then performed correlation and ROC analysis to evaluate the performance of cystine parameters to predict stone activity. RESULTS: During a median followup of 70.6 months (range 2.2 to 274.6) 85 stone events occurred which could be linked to a recent urine collection. Cystine capacity was significantly greater for quiescent urine than for stone event urine (mean ± SD 48 ± 107 vs -38 ± 163 mg/l, p <0.001). Cystine capacity significantly correlated inversely with stone activity (r = -0.29, p <0.001). Capacity also correlated highly negatively with supersaturation (r = -0.88, p <0.001) and concentration (r = -0.87, p <0.001). Using the suggested cutoff of greater than 150 mg/l had only 8.0% sensitivity to predict stone quiescence. Decreasing the cutoff to 90 mg/l or greater improved sensitivity to 25.2% while maintaining specificity at 90.9%. CONCLUSIONS: Our results suggest that the target for capacity should be lower than previously advised.

Duke Scholars

Altmetric Attention Stats
Dimensions Citation Stats

Published In

J Urol

DOI

EISSN

1527-3792

Publication Date

February 2018

Volume

199

Issue

2

Start / End Page

495 / 499

Location

United States

Related Subject Headings

  • Young Adult
  • Urology & Nephrology
  • Urinary Calculi
  • Recurrence
  • ROC Curve
  • Prospective Studies
  • Middle Aged
  • Male
  • Humans
  • Follow-Up Studies
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Friedlander, J. I., Antonelli, J. A., Canvasser, N. E., Morgan, M. S. C., Mollengarden, D., Best, S., & Pearle, M. S. (2018). Do Urinary Cystine Parameters Predict Clinical Stone Activity? J Urol, 199(2), 495–499. https://doi.org/10.1016/j.juro.2017.09.034
Friedlander, Justin I., Jodi A. Antonelli, Noah E. Canvasser, Monica S. C. Morgan, Daniel Mollengarden, Sara Best, and Margaret S. Pearle. “Do Urinary Cystine Parameters Predict Clinical Stone Activity?J Urol 199, no. 2 (February 2018): 495–99. https://doi.org/10.1016/j.juro.2017.09.034.
Friedlander JI, Antonelli JA, Canvasser NE, Morgan MSC, Mollengarden D, Best S, et al. Do Urinary Cystine Parameters Predict Clinical Stone Activity? J Urol. 2018 Feb;199(2):495–9.
Friedlander, Justin I., et al. “Do Urinary Cystine Parameters Predict Clinical Stone Activity?J Urol, vol. 199, no. 2, Feb. 2018, pp. 495–99. Pubmed, doi:10.1016/j.juro.2017.09.034.
Friedlander JI, Antonelli JA, Canvasser NE, Morgan MSC, Mollengarden D, Best S, Pearle MS. Do Urinary Cystine Parameters Predict Clinical Stone Activity? J Urol. 2018 Feb;199(2):495–499.
Journal cover image

Published In

J Urol

DOI

EISSN

1527-3792

Publication Date

February 2018

Volume

199

Issue

2

Start / End Page

495 / 499

Location

United States

Related Subject Headings

  • Young Adult
  • Urology & Nephrology
  • Urinary Calculi
  • Recurrence
  • ROC Curve
  • Prospective Studies
  • Middle Aged
  • Male
  • Humans
  • Follow-Up Studies