Can the Presence of Crystalluria Predict Stone Formation in Patients with Cystinuria?

• Published in: Journal of endourology Vol. 30; no. 5; p. 609
• Main Authors: Wong, Kathie A, Pardy, Caroline, Pillay, Soma, Athanasiou, Thanos, Rottenberg, Giles, Bultitude, Matthew, Chandra, Ashish, Thomas, Kay
• Format: Journal Article
• Language: English
• Published: United States 01.05.2016
• Subjects: Adolescent; Adult; Area Under Curve; Biomarkers - urine; Child; Child, Preschool; Crystallization; Cystinuria - complications; Cystinuria - diagnosis; Cystinuria - urine; Female; Humans; Infant; Male; Middle Aged; Sensitivity and Specificity; Statistics, Nonparametric; Urinalysis; Urinary Calculi - complications; Urinary Calculi - diagnosis; Urinary Calculi - urine; Young Adult
• ISSN: 1557-900X
• DOI: 10.1089/end.2015.0692

To determine the feasibility of crystalluria as a biomarker for stone disease in patients with cystinuria. All patients attending a multidisciplinary cystinuria clinic provided early morning urine (EMU) and clinic urine (CU) samples for crystal measurement over a 2-year period (August 1, 2010, to July 31, 2012). Association between presence of crystals, presence of stone(s), and new stone growth (NSG) was determined using the chi-square test. Crystal numbers in EMU and CU were compared in patients with stones/NSG and no stones/stable disease using the Mann-Whitney U test. There was a statistically significant difference between the presence of crystalluria and presence of stones for CU (chi-square test = 5.86, df = 1, p = 0.02) but not EMU (chi-square test = 1.92, df = 1, p = 0.17) and between the presence of crystalluria and NSG for CU (chi-square test = 8.10, df = 1, p = 0.004) but not EMU (chi-square test = 1.32, df = 1, p = 0.25). Patients with stones and NSG have higher levels of crystalluria in CU than patients with no stones or stable disease (stones, median = 41, interquartile range [IQR] = 600 vs median = 0, IQR = 21, p = 0.01; NSG, median = 49, IQR = 525 vs median = 0, IQR = 40, p = 0.01). The presence of crystalluria in CU samples is associated with the presence of stones. Crystalluria is comparable to ultrasound and may serve as a useful adjunct to predict whether a patient with cystinuria has stones, which could guide the frequency of clinic review and imaging.