title: High within-day variability of fecal calprotectin levels in patients with active ulcerative colitis: what is the best timing for stool sampling?
abstract: BACKGROUND
  Fecal calprotectin (FC) is considered the best noninvasive way to assess disease activity in ulcerative colitis (UC). However, it is not known which is the more suitable moment for stool sampling in patients with increased stool frequency. The aims of this study were to assess the intraindividual variation of FC within day and to evaluate if the first bowel movement in the morning is the more suitable sample for FC measurement in patients with acute flares of UC.
  
  
  METHODS
  Patients admitted because of active UC were invited to collect samples from several bowel movements (including the first in the morning) during the same day providing their ordinal chronology. FC was measured by means of a quantitative rapid point-of-care test based on lateral flow assay immunochromatography.
  
  
  RESULTS
  Eighteen patients were included for a total of 56 stool samples. Most patients had extensive UC and severe disease activity. Within-day FC values varied widely, and the median coefficient of variation was 40% (5%-114%) with a median range of variation of FC values of 3887 mg/kg (69-9946). The sample from the first stool in the morning obtained the highest individual FC within-day value in 33.3% of cases and the lowest in 38.9%.
  
  
  CONCLUSIONS
  FC values widely vary between motions in patients with active UC. Stool sample collection from the first bowel movement in the morning does not ensure the highest or lowest within-day FC value. In patients with overt active UC, a single FC determination should not be used as the basis for therapeutic strategies.
authors: *Hospital Universitari Germans Trias i Pujol, Ciberehd, Badalona, Spain; and †Universitat Autònoma de Barcelona, Barcelona, Spain.
authors: Margalida
authors: M
authors: Calafat
authors: Eduard
authors: E
authors: Cabré
authors: Míriam
authors: M
authors: Mañosa
authors: Triana
authors: T
authors: Lobatón
authors: Laura
authors: L
authors: Marín
authors: Eugeni
authors: E
authors: Domènech
mesh_terms: D015415:Biomarkers / Q000032:analysis*; D003093:Colitis, Ulcerative / Q000175:diagnosis* / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005243:Feces / Q000737:chemistry*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D039841:Leukocyte L1 Antigen Complex / Q000032:analysis*; D008297:Male; D011379:Prognosis; D012307:Risk Factors; D012720:Severity of Illness Index; D013997:Time Factors
chemical_list: D015415:Biomarkers; D039841:Leukocyte L1 Antigen Complex