RDW can be a useful additional marker in diagnosing Crohn's disease and ulcerative colitis

Anaemia is a common complication in patients with inflammatory bowel diseases (IBD-Crohn's disease [CD], ulcerative colitis [UC]) and is mainly caused by iron malabsorption and intestinal bleeding. Red blood cell distribution width (RDW) provides a quantitative measure of the size variability within the red blood cell population and may be increased even before iron deficiency becomes obvious. Recent data suggest that RDW could be a reliable marker in differentiating between CD and UC. The aim of our study was to retrospectively evaluate whether RDW can help to differentiate the two forms of IBD in daily clinical practice, and whether a correlation between RDW and the activity of IBD is demonstrable. Patients and methods. The clinical records of 176 patients were reviewed; 92 patients with CD (57 females, 35 males; mean age 37.5 years, range 17–73), 84 with UC (43 females, 41 males; mean age 44.4 years, range 16–81). RDW values measured in an active and in an inactive period of the diseases were assessed. Disease activity was estimated by serum iron level, C-reactive protein (CRP) level, erythrocyte sedimentation rate (ESR) and Crohn's disease activity index (CDAI)/Clinical activity index (CAI). The relations between these parameters and RDW, and between the RDW values in the two patient groups both in the active and in the inactive period of the diseases were statistically analyzed. Results. RDW was increased in 53.2% of the patients with inactive CD vs. 36.8% of the patients with inactive UC, representing a statistically significant difference (14.3 vs. 13.8, P=0.05). However, a significant correlation could not be detected between the RDW values of CD and UC in the active period of the diseases (14.7 vs. 14.4, P=0.393). Mean RDW was significantly increased in the active form of both CD and UC compared to the normal values of RDW. Conclusion. According to our results, RDW did not prove to be an effective marker in differentiating CD and UC in the active period of the diseases. However, it could be a useful and inexpensive additional marker in diagnosing IBD.