Laboratory evaluation of inflammatory bowel disease

Although clinical history and physical exam may raise suspicion of Crohn disease (CD) or ulcerative colitis (UC), a focused laboratory evaluation can facilitate further differentiation between inflammatory bowel disease (IBD) and non-inflammatory bowel disease—in particular, infectious processes and functional bowel disorders (Table 18.1). These blood and stool studies, in combination with clinical presentation (thorough history, including family history of IBD or other autoimmune conditions, and physical examination), can help determine which child may require more extensive or invasive testing, such as radiological and endoscopic evaluation. Moreover, the blood and stool evaluations may also provide insight into the severity of disease, if indeed IBD (i.e., prognostication), and potentially aid in phenotyping the disease (CD vs. UC). The first part of this review will focus on the evaluation of blood tests in the work-up of a child with suspected IBD. Initially, the nonspecific markers of disease (e.g., anemia) and inflammation (e.g., C-reactive protein (CRP), and erythrocyte sedimentation rate, (ESR)) will be discussed. Subsequently, the more“ specific ”markers of IBD will be reviewed, and then, stool tests which can be used to potentially delineate between IBD and non-IBD will be discussed.