title: Within-Stool and Within-Day Sample Variability of Fecal Calprotectin in Patients With Inflammatory Bowel Disease: A Prospective Observational Study.
abstract: The use of fecal calprotectin (FC) as a stool biomarker for differentiating inflammatory bowel disease (IBD) from IBS has been well validated, and there is a strong correlation between FC and the presence of endoscopic inflammatory lesions. However, recent studies have demonstrated intraindividual sample variability in patients with IBD, possibly limiting the reliability of using a single sample for monitoring disease activity. Our aim was to assess the within-stool and within-day sample variability of FC concentrations in patients with IBD.
  
  
  
  We examined a cross-sectional cohort of 50 adult IBD patients. Eligible patients were instructed to collect 3 samples from different parts of the stool from their first bowel movement of the day and 3 samples from each of up to 2 additional bowel movements within 24 hours. FC concentrations were measured by a rapid, quantitative point-of-care test using lateral flow technology (Quantum Blue). Descriptive statistics were used to assess FC variability within a single bowel movement and between different movements at different FC positivity cutoffs.
  
  
  
  Within a single bowel movement, there was clinically significant sample variability ranging from 8% to 23% depending on the time of the day or on the FC positivity cutoff value. Between bowel movements, there was clinically significant sample variability ranging from 13% to 26% depending on the FC positivity cutoff.
  
  
  
  Considering a single FC sample, the first sample of the day with an FC positivity cutoff of 250 μg/g provided the most reliable indication of disease activity.
authors.affiliation: Division of Gastroenterology, University of Alberta, Edmonton, AB, Canada.
authors.forename: Lillian
authors.initials: L
authors.lastname: Du
authors.forename: Rae
authors.initials: R
authors.lastname: Foshaug
authors.forename: Vivian W
authors.initials: VW
authors.lastname: Huang
authors.forename: Karen I
authors.initials: KI
authors.lastname: Kroeker
authors.forename: Levinus A
authors.initials: LA
authors.lastname: Dieleman
authors.forename: Brendan P
authors.initials: BP
authors.lastname: Halloran
authors.forename: Karen
authors.initials: K
authors.lastname: Wong
authors.forename: Richard N
authors.initials: RN
authors.lastname: Fedorak
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005243:Feces / Q000737:chemistry*; D005260:Female; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000175:diagnosis / Q000473:pathology*; D039841:Leukocyte L1 Antigen Complex / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D013997:Time Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers; D039841:Leukocyte L1 Antigen Complex