title: Can the Presence of Crystalluria Predict Stone Formation in Patients with Cystinuria?
abstract: 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.
authors.affiliation: 1 The Urology Centre, Guy's and St. Thomas' NHS Foundation Trust , London, United Kingdom .
authors.forename: Kathie A
authors.initials: KA
authors.lastname: Wong
authors.affiliation: 1 The Urology Centre, Guy's and St. Thomas' NHS Foundation Trust , London, United Kingdom .
authors.forename: Caroline
authors.initials: C
authors.lastname: Pardy
authors.affiliation: 2 Department of Cytopathology, Guy's and St. Thomas' NHS Foundation Trust , London, United Kingdom .
authors.forename: Soma
authors.initials: S
authors.lastname: Pillay
authors.affiliation: 3 Department of Surgery and Cancer, Imperial College London , London, United Kingdom .
authors.forename: Thanos
authors.initials: T
authors.lastname: Athanasiou
authors.affiliation: 4 Department of Radiology, Guy's and St. Thomas' NHS Foundation Trust , London, United Kingdom .
authors.forename: Giles
authors.initials: G
authors.lastname: Rottenberg
authors.affiliation: 1 The Urology Centre, Guy's and St. Thomas' NHS Foundation Trust , London, United Kingdom .
authors.forename: Matthew
authors.initials: M
authors.lastname: Bultitude
authors.affiliation: 2 Department of Cytopathology, Guy's and St. Thomas' NHS Foundation Trust , London, United Kingdom .
authors.forename: Ashish
authors.initials: A
authors.lastname: Chandra
authors.affiliation: 1 The Urology Centre, Guy's and St. Thomas' NHS Foundation Trust , London, United Kingdom .
authors.forename: Kay
authors.initials: K
authors.lastname: Thomas
mesh_terms: D000293:Adolescent; D000328:Adult; D019540:Area Under Curve; D015415:Biomarkers / Q000652:urine; D002648:Child; D002675:Child, Preschool; D003460:Crystallization; D003555:Cystinuria / Q000150:complications / Q000175:diagnosis* / Q000652:urine; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D016482:Urinalysis; D014545:Urinary Calculi / Q000150:complications / Q000175:diagnosis* / Q000652:urine; D055815:Young Adult
chemical_list: D015415:Biomarkers