title: Rectal nitric oxide and fecal calprotectin in inflammatory bowel disease.
abstract: OBJECTIVE
  The assessment of intestinal inflammation in patients with inflammatory bowel disease (IBD) remains a difficult challenge. Both rectal nitric oxide (NO) and fecal calprotectin can be measured using non-invasive methods and are emerging as promising inflammatory markers in IBD. In this study the aim was to compare calprotectin and NO levels in IBD patients.
  
  
  METHODS
  Rectal NO was measured tonometrically in 23 healthy volunteers and 32 patients with IBD. In addition, we collected stool samples from all subjects for measurement of fecal calprotectin and nitrate/nitrite (NO metabolites).
  
  
  RESULTS
  Patients with IBD had greatly increased NO and calprotectin levels compared to healthy volunteers (p <0.001). In addition, the nitrate levels were slightly increased in IBD patients. A weak correlation was found between rectal NO levels, disease activity and number of loose stools in IBD patients (Spearman's rho 0.37 and 0.51, respectively; p <0.05). Fecal calprotectin correlated only with age (Spearman's rho 0.51; p <0.01). However, no correlation was found between NO and calprotectin.
  
  
  CONCLUSIONS
  Both rectal NO and fecal calprotectin are greatly increased during bowel inflammation, but they may reflect different parts of the inflammatory process. Future studies will elucidate the clinical usefulness of these two markers.
authors.affiliation: Department of Physiology and Pharmacology Karolinska Institutet, Stockholm, Sweden. claudia.reinders@ki.se
authors.forename: Claudia A
authors.initials: CA
authors.lastname: Reinders
authors.forename: Daisy
authors.initials: D
authors.lastname: Jonkers
authors.forename: Emmellie A
authors.initials: EA
authors.lastname: Janson
authors.forename: Reinhold W
authors.initials: RW
authors.lastname: Stockbrügger
authors.forename: Ellen E
authors.initials: EE
authors.lastname: Stobberingh
authors.forename: Per M
authors.initials: PM
authors.lastname: Hellström
authors.forename: Jon O
authors.initials: JO
authors.lastname: Lundberg
mesh_terms: D015415:Biomarkers / Q000032:analysis; D003424:Crohn Disease / Q000175:diagnosis*; D005243:Feces / Q000737:chemistry*; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000175:diagnosis*; D039841:Leukocyte L1 Antigen Complex / Q000032:analysis*; D009426:Netherlands; D009566:Nitrates / Q000032:analysis; D009569:Nitric Oxide / Q000032:analysis*; D009573:Nitrites / Q000032:analysis; D012016:Reference Values
chemical_list: D015415:Biomarkers; D039841:Leukocyte L1 Antigen Complex; D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide