title: Determining normal values of urinary phosphorus excretion in 3913 healthy children aged 2-18 to aid early diagnosis and treatment for urolithiasis.
abstract: OBJECTIVE
  This study determined the specific reference values for urinary phosphorus excretion in healthy children and adolescents aged 2-18 years and evaluated whether they changed with age during growth and were gender dependent.
  
  
  METHODS
  We enrolled 3913 healthy children and adolescents aged 2-18 years to this study. The study population was divided into age groups, and the analysis was performed in one-year periods, separately for boys and girls. Urinary phosphorus excretion was analysed using four categories: P1 in mmol/24 hour units, P2 in mmol/kg/24 hours, P3 in mmol/1.73 m2/24 hours and P4 in mmol/mmol creatinine.
  
  
  RESULTS
  Clear differences in urinary exertion for girls and boys were observed as well as systematic changes with age. The boys presented with significantly higher daily urinary phosphorus excretion independent of its manner of expression (p < 0.001). The median urinary phosphorus (P1) rose with age (p < 0.001). Percentile tables of phosphorous exertion are presented.
  
  
  CONCLUSIONS
  This was the largest study of urinary phosphate excretion based on a randomly selected sample of girls and boys aged 2-18 years. It highlights the importance of determining phosphorus reference values for children of different ages to provide early diagnosis and treatment for urolithiasis.
authors.affiliation: Department of Paediatrics and Nephrology, Medical University of Bialystok, Bialystok, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Taranta-Janusz
authors.affiliation: Faculty of Physics, University of Białystok, Białystok, Poland.
authors.forename: Łukasz
authors.initials: Ł
authors.lastname: Łabieniec
authors.affiliation: Department of Paediatrics and Nephrology, Medical University of Bialystok, Bialystok, Poland.
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Porowski
authors.affiliation: Faculty of Physics, University of Białystok, Białystok, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Szymański
authors.affiliation: Department of Medical Chemistry, Medical University of Bialystok, Bialystok, Poland.
authors.forename: Halina
authors.initials: H
authors.lastname: Porowska
authors.affiliation: Department of Paediatrics and Nephrology, Medical University of Bialystok, Bialystok, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Wasilewska
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000652:urine; D005260:Female; D006801:Humans; D008297:Male; D010758:Phosphorus / Q000652:urine*; D012016:Reference Values; D012189:Retrospective Studies; D052878:Urolithiasis
chemical_list: D010758:Phosphorus; D003404:Creatinine
keywords: Children; Phosphorus; Reference values; Urinary Phosphate excretion urolithiasis