title: Risk factors for urinary stones in healthy schoolchildren with and without a family history of nephrolithiasis.
abstract: BACKGROUND
  The prevalence of lithiasis is increasing at all ages. This study aimed to assess the crystallization risk in urine from healthy school children and to determine urinary parameters that are most associated with it.
  
  
  METHODS
  Urine samples were obtained from 184 children aged 5-12 years: a spot sample collected in the afternoon, and a 12-h overnight sample. Information was obtained regarding family histories of lithiasis. Urine volume, pH, and biochemical parameters of stone risk were measured. Crystallization risk was defined by the presence of specific urine conditions that had previously been associated with stone formation in vitro.
  
  
  RESULTS
  Crystallization risk was observed in 15 % of spot urine samples and 54 % of 12-h samples. Metabolic abnormalities and a low urinary volume were more frequently detected in children with crystallization risk. Calcium excretion and calcium/citrate ratio were higher in children with a family history of lithiasis.
  
  
  CONCLUSIONS
  We observed a high prevalence of crystallization risk in urine, especially in children with a family history of the disease. Low urinary volume was the factor most associated with increased risk. Adequate fluid intake at an early age may be a simple and effective measure to reduce the incidence of nephrolithiasis.
authors.affiliation: Universitary Institute of Health Sciences Research (IUNICS), University of Balearic Islands, Carretera de Valldemossa km 7.5, 07122, Palma de Mallorca, Spain. currisaez@telefonica.net
authors.forename: Concepción
authors.initials: C
authors.lastname: Sáez-Torres
authors.forename: Félix
authors.initials: F
authors.lastname: Grases
authors.forename: Dolores
authors.initials: D
authors.lastname: Rodrigo
authors.forename: Ana María
authors.initials: AM
authors.lastname: García-Raja
authors.forename: Cristina
authors.initials: C
authors.lastname: Gómez
authors.forename: Guillem
authors.initials: G
authors.lastname: Frontera
mesh_terms: D015415:Biomarkers / Q000652:urine; D002118:Calcium / Q000652:urine; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D019343:Citric Acid / Q000652:urine; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D053040:Nephrolithiasis / Q000235:genetics*; D010375:Pedigree; D018570:Risk Assessment; D012307:Risk Factors; D016482:Urinalysis; D014545:Urinary Calculi / Q000175:diagnosis / Q000209:etiology* / Q000235:genetics / Q000503:physiopathology / Q000652:urine; D014554:Urination
chemical_list: D015415:Biomarkers; D019343:Citric Acid; D002118:Calcium