title: Urinary oxalate excretion in urolithiasis and nephrocalcinosis.
abstract: OBJECTIVE
  To investigate urinary oxalate excretion in children with urolithiasis and/or nephrocalcinosis and to classify hyperoxaluria (HyOx).
  
  
  METHODS
  A total of 106 patients were screened. In those in whom the oxalate: creatinine ratio was increased, 24 hour urinary oxalate excretion was measured. Liver biopsy and/or genomic analysis was performed if primary hyperoxaluria (PH) was suspected. Stool specimens were examined for Oxalobacter formigenes in HyOx not related to PH type 1 or 2 (PH1, PH2) and in controls.
  
  
  RESULTS
  A total of 21 patients screened had HyOx (>0.5 mmol/24 h per 1.73 m(2)); they were classified into five groups. Eleven had PH (PH1 in nine and neither PH1 nor PH2 in two). Six had secondary HyOx: two enteric and four dietary. Four could not be classified. Seven patients had concomitant hypercalciuria. Only one of 12 patients was colonised with O formigenes compared to six of 13 controls.
  
  
  CONCLUSIONS
  HyOx is an important risk factor for urolithiasis and nephrocalcinosis in children, and can coexist with hypercalciuria. A novel type of PH is proposed. Absence of O formigenes may contribute to HyOx not related to PH1.
authors.affiliation: Nephrology Unit, University Children's Hospital, Steinwiesstrasse 75, CH-8032 Zurich, Switzerland. Thomas.Neuhaus@kispi.unizh.ch
authors.forename: T J
authors.initials: TJ
authors.lastname: Neuhaus
authors.forename: T
authors.initials: T
authors.lastname: Belzer
authors.forename: N
authors.initials: N
authors.lastname: Blau
authors.forename: B
authors.initials: B
authors.lastname: Hoppe
authors.forename: H
authors.initials: H
authors.lastname: Sidhu
authors.forename: E
authors.initials: E
authors.lastname: Leumann
mesh_terms: D000293:Adolescent; D002129:Calcium Oxalate / Q000652:urine; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000652:urine; D005260:Female; D006801:Humans; D006959:Hyperoxaluria / Q000652:urine*; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009397:Nephrocalcinosis / Q000652:urine*; D020624:Oxalobacter formigenes; D014545:Urinary Calculi / Q000652:urine*
chemical_list: D002129:Calcium Oxalate; D003404:Creatinine