title: Calcium oxalate urolithiasis in children: urinary promoters/inhibitors and role of their ratios.
abstract: Diagnostic criteria for determination of inclination towards idiopathic calcium oxalate (CaOx) urolithiasis based on biochemical urine parameters are not sufficiently well defined in children. The aim of this study was to determine the risk of CaOx urolithiasis in children from concentrations of calcium, oxalate, citrate, and glycosaminoglycans in urine and their ratios, all standardized in respect to creatinine. We collected and analyzed 24-h urine samples of children with CaOx urolithiasis (n = 61) and compared with urine samples of matched control group of healthy children (n = 25). The study has showed that all stone formers have higher excretion of calcium (mmol/mmol creatinine), calcium/citrate (mol/mmol), and oxalate/(citrate × glycosaminoglycans) ratio (mol Ox × mol cr)/(mol Cit × g GAGs). ROC analysis of these variables gave criteria (>0.28, >1.07, and >0.08, respectively) for distinguishing stone formers from healthy children. Biochemical urine parameters and their ratios (calcium, calcium citrate, and oxalate/(citrate × glycosaminoglycans) enable one to discriminate idiopathic calcium oxalate stone formers from healthy children. Oxalate/(citrate × glycosaminoglycans) ratio per se can serve as an independent risk for stone formation.
  
  
  CONCLUSIONS
  Using biochemical urine parameters and their ratios such as calcium, calcium/citrate, and oxalate/(citrate × glycosaminoglycans) enables one to determine diagnostic criteria towards idiopathic calcium oxalate urolithiasis in children. What is known: • The role of urine calcium as a promoter in calcium oxalate urolithiasis is well established. • Seldom used calcium/citrate ratio is acknowledged as a risk factor for calcium/oxalate urolithiasis. What is new: • The values of calcium and citrate in clinically and genetically proven idiopathic calcium oxalate urolithiasis make calcium/citrate ratio useful for diagnostic purposes in such stone formers. • Rarely used calcium independent oxalate/(citrate x glycosaminoglycans) ratio serves as the second best high specificity marker for idiopathic calcium oxalate urolithiasis.
authors.affiliation: University of Zagreb School of Medicine, Salata 3, 10000, Zagreb, Croatia.
authors.forename: Daniel
authors.initials: D
authors.lastname: Turudic
authors.affiliation: Children's Hospital Srebrnjak, 10000, Zagreb, Croatia.
authors.forename: Danica
authors.initials: D
authors.lastname: Batinic
authors.affiliation: Department of Nuclear Medicine, University Hospital Center Zagreb, Kispaticeva 12, 10000, Zagreb, Croatia.
authors.forename: Anja Tea
authors.initials: AT
authors.lastname: Golubic
authors.affiliation: Department of Clinical Laboratory Diagnostic, University Hospital Center Zagreb, Kispaticeva 12, 10000, Zagreb, Croatia.
authors.forename: Mila
authors.initials: M
authors.lastname: Lovric
authors.affiliation: Department of Pediatric Nephrology, Dialysis and Transplantation, University of Zagreb School of Medicine, University Hospital Center Zagreb, Kispaticeva 12, 10000, Zagreb, Croatia. danko.milosevic@kbc-zagreb.hr.
authors.forename: Danko
authors.initials: D
authors.lastname: Milosevic
mesh_terms: D002118:Calcium / Q000652:urine; D019355:Calcium Citrate / Q000652:urine; D002129:Calcium Oxalate / Q000652:urine*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D012372:ROC Curve; D012307:Risk Factors; D018709:Statistics, Nonparametric; D052878:Urolithiasis / Q000652:urine*
chemical_list: D002129:Calcium Oxalate; D019355:Calcium Citrate; D002118:Calcium
keywords: Calcium; Children; Citrate; Glycosaminoglycans; Oxalate; Urolithiasis