B2 microglobulin: Is it a reliable marker of activity in inflammatory bowel disease?

OBJECTIVES: The aims of this study were to investigate a possible positive correlation between B2-microglobulin (B2-M) serum levels and the severity and activity of inflammatory bowel disease (IBD); and to examine whether B2-M levels reflect IBD extent. METHODS: We examined B2-M serum levels in 87 ulcerative colitis (UC) patients, 74 with Crohn's disease (CD) and 68 control subjects, using an enzymatic method. The reliability of the measuring method was assessed by evaluating serum B2-M in 18 patients suffering from chronic renal failure (CRF). The severity and activity of IBD was estimated using the van Hees Activity Index and the True-love-Witts criteria for CD and UC patients respectively. Endoscopic evaluation for UC patients was done according to Baron's et nl. classification; Riley's et al. criteria were used for histological evaluation. RESULTS: B2-M serum levels were significantly increased in all CD patients except those in remission. After 6 months treatment a second blood sample taken from CD patients with initially elevated B2-M levels proved to be compatible with CD severity at that time. Such a positive correlation was not assessed in UC patients; therefore, a second blood sample was considered unnecessary. Furthermore, CD patients with pancolitis, ileal-caecal, or small intestinal disease had higher B2-M levels than those with left-sided, anal, or perianal disease. CONCLUSIONS: B2-M serum levels could prove to be a useful marker in assessing not only the activity, severity, and extent of CD but the treatment efficacy as well. (C) 2001 by Am. Cell. of Gastroenterology.