Serological markers in inflammatory bowel disease: a review of their clinical utility.

Background: Several antibodies, also called serological markers, are associated with specific forms, disease behavior and phenotype of inflammatory bowel disease (IBD).
Aim: Summarize and analyze the evidence of the utility of serologic markers in IBD, making emphasis on their clinical utility and behavior between populations.
Material and Methods: Relevant articles were located by computer-assisted search of PubMed (since January 1979 until December 2008).
Results: Anti-Saccharomyces cerevisiae antibodies (ASCA) and perinuclear Anti-neutrophil Cytoplasmic Antibodies (pANCA) are the best studied serological markers. Assessing both ASCA and pANCA allows a better differentiation of Crohn's disease (CD) from ulcerative colitis (UC) than by using the individual tests alone. The ASCA+/pANCA- phenotype is characteristic of CD, while the ASCA-/pANCA+ phenotype is found in UC. The interest on atypical ANCA is growing as it may be a useful tool to distinguish between different IBD forms. Newer markers derived from various microbial species of the gut and glycan markers are of interest as they offer new ways to stratify patients into serologic subgroups. These serological markers may act as prognostic indicators of the severity and behavior of IBD, but more studies are necessary to determine their utility.
Conclusions: There is emerging evidence that combining serological markers may increase the accuracy of diagnosis of a specific form of IBD or its behavior, but the perfect assay or combination of antibodies has not been discovered. They have several limitations, therefore clinicians must be aware of the evidence on serological markers, interpret them with caution and always correlate with the clinical picture.