Serum beta 2-microglobulin as a biomarker in inflammatory bowel disease

AIM: To investigate the diagnostic utility of beta 2 microglobulin (B2-M) levels and analyze this correlation with the activity of inflammatory bowel disease (IBD). METHODS: Overall, 78 IBD patients and 30 healthy controls were enrolled in the study. We examined B2-M serum levels in 43 ulcerative colitis (UC) patients, 35 with Crohn's disease (CD) and 30 control subjects, using an enzymatic method. Patients were divided into two groups according to two disease types: active and in remission. Subjects were also divided into two subgroups according to extent of the disease: left-side and pancolitis for UC and ileitis and ileocolitis for CD. All groups were compared for mean serum B2-M levels and also examined to see whether there was a correlation between serum B2-M levels and other inflammatory markers. RESULTS: The mean serum B2-M levels in the control group, UC and CD were 1.71, 2.41 and 2.24 respectively. B2-M values ≥ 1.96 mg/L had a 62% sensitivity, 76% specificity, a 79% positive predictive value, and a 58% negative predictive value for UC patients. B2-M values ≥ 1.70 mg/L had 80% sensitivity, 53% specificity, 66% positive predictive value, and 69% negative predictive value for CD patients. Mean B2-M values were significantly higher in ulcerative colitis and Crohn's disease patients than in healthy controls (UC 2.41 ± 0.87 vs 1.71 ± 0.44, P = 0.002; CD 2.24 ± 1.01 vs 1.71 ± 0.44, P = 0.033). Also, mean B2-M values were significantly higher in active disease when compared to patients in remission (UC 2.66 ± 0.92 vs 1.88 ± 0.41, P = 0.004; CD 2.50 ± 1.15 vs 1.73 ± 0.31, P = 0.033). The difference between groups (UC and CD) in terms of serum B2-M levels was statistically insignificant (2.41 ± 0.87 vs 2.24 ± 1.01, P > 0.05 respectively). CONCLUSION: Serum B2-M levels may be used as an activity parameter in IBD.