title: Urinary metabolic evaluations in solitary and recurrent stone forming children.
abstract: OBJECTIVE
  We have previously reported a high rate of urinary metabolic abnormalities in stone forming children compared to normal controls. At our institution a 24-hour urine evaluation is initiated after the first stone episode in children, to measure stone risk indices. The purpose of this study was to determine which children are at the greatest risk for recurrent stone formation.
  
  
  METHODS
  A retrospective cohort study was performed to assess urinary metabolic profiles in children with urolithiasis. In all patients 24-hour urine collections were performed and evaluated elsewhere. Urine chemistry assessments such as calcium and citrate were adjusted for creatinine and weight. Calcium oxalate supersaturation was measured. Patients were stratified as solitary or recurrent stone formers based on review of the medical record. Univariate analysis between means was performed with a 2-tailed t test.
  
  
  RESULTS
  A total of 148 samples from 88 solitary stone formers and 84 samples from 51 recurrent stone formers were evaluated. Age and gender were well matched between the 2 groups. Timed urinary calcium levels referenced to creatinine and citrate were significantly higher in patients with recurrent stones. Supersaturation levels of calcium oxalate were higher in recurrent stone formers but did not reach statistical significance.
  
  
  CONCLUSIONS
  There are significant differences in 24-hour urinary calcium levels between solitary and recurrent calcium stone forming children. A patient with increased urinary calcium indices on a 24-hour specimen may benefit from more aggressive initial dietary and pharmacological treatment to prevent stone recurrence.
authors.affiliation: Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039, USA. bob.defoor@cchmc.org
authors.forename: William
authors.initials: W
authors.lastname: DeFoor
authors.forename: Eugene
authors.initials: E
authors.lastname: Minevich
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Jackson
authors.forename: Pramod
authors.initials: P
authors.lastname: Reddy
authors.forename: Curtis
authors.initials: C
authors.lastname: Clark
authors.forename: Curtis
authors.initials: C
authors.lastname: Sheldon
authors.forename: John
authors.initials: J
authors.lastname: Asplin
mesh_terms: D000293:Adolescent; D002648:Child; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D014545:Urinary Calculi / Q000453:epidemiology / Q000378:metabolism / Q000652:urine*