title: Effects of timing, sex, and age on site-specific gastrointestinal permeability testing in children and adults.
abstract: OBJECTIVE
  Measurement of gastrointestinal (GI) permeability is commonly used in research and often used clinically. Despite its utility, little is known about sugar excretion timeframes or the potential effects of age and sex on GI permeability testing. We seek to determine the timeframes of sugar excretion and the potential effects of age and sex on urinary recovery of the sugars.
  
  
  METHODS
  Healthy adults (n = 17) and children (n = 15) fasted 4 hours after the evening meal and then ingested a solution of sucrose, lactulose, mannitol, and sucralose. Urine was collected at 30, 60, and 90 minutes after ingestion and then each time the subjects voided during the next 24 hours. Each urine void was collected separately.
  
  
  RESULTS
  Median age for the adults was 47.5 years (range 21-57 years) and for children 10 years (range 5-17 years). There were no differences between children and adults in mean percent dose of sugar recovered. The time of peak urinary recovery of the sugars was generally similar between children and adults. Sucrose urinary recovery declined with age (P = 0.008; r2 = 0.19) unrelated to sex. Lactulose and sucralose urinary recovery declined with age in females (P = 0.05, r2 = 0.24 and P = 0.011, r2 = 0.41; respectively) but not in males.
  
  
  CONCLUSIONS
  Overall, sugar urinary recovery is comparable in children and adults. Specific sugar urinary recovery may change as a function of age and/or sex. These results need to be taken into account when planning and interpreting gastrointestinal permeability studies.
authors.affiliation: Phoenix Children's Hospital, Phoenix, Arizona, USA.
authors.forename: Mark E
authors.initials: ME
authors.lastname: McOmber
authors.forename: Ching-Nan
authors.initials: CN
authors.lastname: Ou
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Shulman
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D035843:Biomedical Research / Q000379:methods; D002463:Cell Membrane Permeability; D002648:Child; D002675:Child, Preschool; D019422:Dietary Sucrose / Q000493:pharmacokinetics* / Q000652:urine; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism*; D007792:Lactulose / Q000493:pharmacokinetics / Q000652:urine; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D013395:Sucrose / Q000031:analogs & derivatives / Q000493:pharmacokinetics / Q000652:urine; D013997:Time Factors; D055815:Young Adult
chemical_list: D019422:Dietary Sucrose; D007792:Lactulose; D013395:Sucrose; C026285:trichlorosucrose