title: Spot urinary creatinine excretion in pervasive developmental disorders.
abstract: BACKGROUND
  Excretion of creatinine in urine represents the end-point of endogenous energy transfer from stored adenosine triphosphate in skeletal and cardiac muscle. Measurement of urinary creatinine is commonly used to correct for total urine concentration. Various quantitative measures of compounds suspected to be either pathological to, or indicative of, possible therapeutic interventions for Pervasive Developmental Disorders (PDD) have relied extensively on spot creatinine as a ratio quantity, although this important metabolite has not been exclusively studied within this population.
  
  
  METHODS
  Levels of urinary creatinine in spot urine samples were analyzed for a group of children diagnosed with PDD (n=24; median age, 75 months; range, 39-137 months) and a control group (n=50; median age, 109 months; range, 59-140 months). Diagnosis of PDD was confirmed using the Autism Diagnostic Interview-Revised. Samples were collected and analyzed blind for creatinine content using an improved Jaffe's reaction method.
  
  
  RESULTS
  Controlling for sample pH and body mass index, a significant decrease in urinary creatinine concentration was found in the PDD group compared to controls using a Mann-Whitney two-tailed ranks test (P=0.001).
  
  
  CONCLUSIONS
  Further studies of protein catabolism and renal function in autism are required to ascertain the relevance of decreased spot urinary creatinine excretion identified in this preliminary study. Issues regarding the use of single urine creatinine measurements and associated confounding variables are discussed in light of the findings, together with recommendations to use other internal or external standards for the quantification of urinary compounds in PDD research.
authors.affiliation: Autism Research Unit, School of Health, Natural & Social Sciences, University of Sunderland, Sunderland, UK. paul.whiteley@sunderland.ac.uk
authors.forename: Paul
authors.initials: P
authors.lastname: Whiteley
authors.forename: Rosemary
authors.initials: R
authors.lastname: Waring
authors.forename: Lee
authors.initials: L
authors.lastname: Williams
authors.forename: Libuse
authors.initials: L
authors.lastname: Klovrza
authors.forename: Frances
authors.initials: F
authors.lastname: Nolan
authors.forename: Susan
authors.initials: S
authors.lastname: Smith
authors.forename: Malcolm
authors.initials: M
authors.lastname: Farrow
authors.forename: Kalliopi
authors.initials: K
authors.lastname: Dodou
authors.forename: W John
authors.initials: WJ
authors.lastname: Lough
authors.forename: Paul
authors.initials: P
authors.lastname: Shattock
mesh_terms: D000367:Age Factors; D049628:Body Size; D016022:Case-Control Studies; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000652:urine*; D002675:Child, Preschool; D003404:Creatinine / Q000652:urine*; D005260:Female; D006801:Humans; D008297:Male; D012737:Sex Factors
chemical_list: D003404:Creatinine