A new, highly sensitive assay for C-reactive protein can aid the differentiation of inflammatory bowel disorders from constipation- and diarrhoea-predominant functional bowel disorders

Eur J Gastroenterol Hepatol. 2002 Apr;14(4):409-12. doi: 10.1097/00042737-200204000-00013.


Background: Patients presenting to gastroenterology clinics with symptoms suggestive of lower-bowel disorders often require extensive investigation to differentiate functional from organic disease. C-reactive protein (CRP) is a sensitive marker of systemic inflammation. Levels of CRP are frequently raised in cases of inflammatory bowel disease (IBD). However, using conventional assays, not all cases of IBD have a detectable level.

Objective: To determine whether a new highly sensitive CRP enzyme-linked immunosorbent assay (ELISA) can aid the differentiation between IBD and functional bowel disorders (FBDs) in gastroenterology outpatients presenting with lower-bowel symptoms.

Methods: Serum was taken from 224 subjects attending a gastroenterology outpatient clinic. Of these, 203 were new patients and 21 were follow-up patients with quiescent colitis. The serum was analysed using a sensitive in-house ELISA. All new patients had a rigid sigmoidoscopy and rectal biopsy. Patients were investigated as deemed appropriate by the attending physician. Notes were reviewed after at least 6 months to determine the final diagnosis.

Results: A cut-off value of 2.3 mg/l had a sensitivity of 100% and a specificity of 67% in differentiating FBD from new cases of IBD. The geometric mean CRP was 0.383 mg/l in the constipation-predominant FBD group, 1.435 mg/l in diarrhoea-predominant FBD, 1.455 mg/l in quiescent IBD, 8.892 mg/l in newly presenting cases of ulcerative colitis, and 13.123 mg/l in newly presenting cases of Crohn's disease.

Conclusion: A new, highly sensitive assay for CRP may help to distinguish FBD from IBD.

Publication types

  • Evaluation Study

MeSH terms

  • Adult
  • C-Reactive Protein / analysis*
  • Colonic Diseases, Functional / diagnosis*
  • Constipation / etiology
  • Diagnosis, Differential
  • Diarrhea / etiology
  • Enzyme-Linked Immunosorbent Assay / methods*
  • Female
  • Humans
  • Inflammatory Bowel Diseases / diagnosis*
  • Male
  • Prospective Studies
  • ROC Curve
  • Sensitivity and Specificity


  • C-Reactive Protein