ABSTRACT
Inflammatory bowel disease (IBD) is a common gastrointestinal tract disease and can be divided into two major groups: ulcerative colitis (UC) and Crohn's disease (CD). These two entities can be diagnosed from a combination of invasive and non-invasive tests as well as a thorough history and physical examination. However, invasive tests are preferred for a definitive diagnosis since the two entities have characteristic features of colonoscopy and biopsy. In this review, the following will be discussed: how non-invasive tests could help detect the presence of IBD, how markers help monitor disease progression, and how the disease responds to treatment. Some of the common markers that are discussed in detail include perinuclear antineutrophil cytoplasmatic antibodies (p-ANCA), anti-Saccharomyces cerevisiae antibodies (ASCA), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), calprotectin, lactoferrin, lipocalin-2 (LCN2), and several other novel markers that are based on bacterial antigens. The best non-invasive tests available for detecting the presence of IBD are serological and fecal markers. Detecting these markers has helped doctors significantly by bringing to their attention the possibility of the presence of IBD. The serological testing can also help distinguish the two forms of IBD since a different combination of markers is elevated in UC and CD. In addition, the symptoms of IBD are non-specific and usually overlap with other gastrointestinal tract disorders, so by finding these serological markers, doctors can proceed with further invasive testing that would give them a definitive diagnosis. That way, invasive testing, such as colonoscopy with biopsy, can be avoided in patients with no suspicion of IBD. The common markers used in the clinical setting to point out the presence of IBD are discussed in detail in this review. Recently, more specific markers derived from bacterial antigens are also used, and their role is discussed, too.
