Assessment of high-sensitivity CRP as a marker of micro-inflammation in irritable bowel syndrome

The diagnosis of irritable bowel syndrome (IBS) is symptom-based. Although considered a functional disease, accumulating evidence supports a low-grade gut inflammation as an element of its pathophysiology. Thus, high-sensitivity C-reactive protein (hs-CRP), a marker of micro inflammation, may be elevated in IBS. Our aim was to assess whether hs-CRP is higher in IBS patients compared to healthy controls (HC) and does it differ among the IBS clinical subgroups and correlate with disease severity.

A diagnostic case control study was conducted in two gastroenterology departments. Eighty-eight IBS patients who were recruited prospectively answered the Rome III diagnostic questionnaire. They all completed the Functional Bowel Disorder Severity Index (FBDSI), dietary, and general health questionnaires. All patients underwent blood sampling for hs-CRP levels. Each IBS patient was matched to four HC by age, gender, and BMI. Blood samples were obtained from the HC at a periodic health survey.

The mean hs-CRP level in the IBS group was significantly higher than in HC (1.17±1.26mg L(-1) vs 0.72±0.91mg L(-1) respectively, P=0.001). Hs-CRP levels were highest in patients with diarrhea-predominant IBS and in patients with greater disease severity. A cut-off value of 1.08mg L(-1) had a sensitivity of 60.2% and a specificity of 68% for differentiating IBS from HC.

Hs-CRP levels are higher in IBS patients than HC, but still in the normal laboratory range. This may reflect the low-grade gut inflammation believed to occur in IBS and support its existence.