title: Decreased Urinary Sodium-to-urinary Creatinine Ratio Identifies Sodium Depletion in Pediatric Acute Gastroenteritis.
abstract: In acute gastroenteritis (AG) fecal losses may cause depletion of sodium (NaD) which may not be recognized because of normal plasma Na (pNa) concentrations. We studied the incidence of this state of normonatremic sodium depletion (NNaD) and the suitability of the urinary Na/urinary creatinine ratio (uNa/uCr) for diagnosing NNaD.
  
  
  METHODS
  16 AG- and 16 healthy control children aged 0.8-15.0 years.
  
  
  METHODS
  Prospective cross sectional pilot study. Measurements of Na, K and creatinine in plasma (p) and urine (u). Calculation of uNa/uCr Ratio, fractional excretion of Na (FENa) and uNa/uK ratio as the hitherto best known parameters of prerenal Na depletion, respectively.
  
  
  RESULTS
  pNa concentrations were normal in 15/16 AG patients (93.8%) with only one subnormal value of 133 mmol/L, and a mean value of 137.9±2.3 mmol/L not different from the normal control group (139.4±2.2 mmol/L). Also, mean uNa concentrations and uNa/uK ratios did not differ between both groups. However, uNa/uCr ratios were below normal in 13/16 AG children (81.3%) but normal in all healthy controls with a significantly lower mean value in the AG group (12.6±8.8 vs. 31.2±8.3 mmol/mmol; p<0.0001). Similarly, 14/16 AG patients (87.5%) had a decreased FENa<0.5% with a mean FENa value significantly lower than in controls (0.36±0.28% vs. 0.95±0.26%, p<0.0001). The good agreement between FENa and uNa/uCr results was also reflected by a high correlation coefficient of r=0.9333.
  
  
  CONCLUSIONS
  The majority of AG patients was found to have NNaD as determined by uNa/uCr and FENa. Calculation of uNa/uCr may be useful for diagnosing NNaD in AG.
authors.affiliation: Department Pediatrics I, Medical University, Innsbruck, Austria.
authors.forename: P
authors.initials: P
authors.lastname: Heinz-Erian
authors.affiliation: Department Pediatrics I, Medical University, Innsbruck, Austria.
authors.forename: Z
authors.initials: Z
authors.lastname: Akdar
authors.affiliation: Pediatric Surgery, Medical University, Innsbruck, Austria.
authors.forename: B
authors.initials: B
authors.lastname: Haerter
authors.affiliation: Department Pediatrics I, Medical University, Innsbruck, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Waldegger
authors.affiliation: Department Pediatrics I, Medical University, Innsbruck, Austria.
authors.forename: T
authors.initials: T
authors.lastname: Giner
authors.affiliation: Department Pediatrics I, Medical University, Innsbruck, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Scholl-Bürgi
authors.affiliation: Department Pediatrics I, Medical University, Innsbruck, Austria.
authors.forename: T
authors.initials: T
authors.lastname: Mueller
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000652:urine*; D003430:Cross-Sectional Studies; D005260:Female; D005759:Gastroenteritis / Q000150:complications* / Q000652:urine; D006801:Humans; D007010:Hyponatremia / Q000175:diagnosis* / Q000209:etiology* / Q000652:urine; D007223:Infant; D008297:Male; D010865:Pilot Projects; D011188:Potassium / Q000652:urine; D011446:Prospective Studies; D012964:Sodium / Q000652:urine*
chemical_list: D012964:Sodium; D003404:Creatinine; D011188:Potassium