REVIEW OF LABORATORY BIOMARKERS OF INFLAMMATORY BOWEL DISEASE

Abstract

Inflammatory bowel disease (IBD), a cluster of chronic, immune–related and long–term disorders that cause fever, abdominal pain/cramping, fatigue, severe and recurrent diarrhoea, rectal bleeding and weight loss, and characterised by inflammation of gastrointestinal tract (GIT), is categorised as crohn’s disease (CD), ulcerative colitis (UC) or IBD unclassified (IBDU). Assessing the diagnosis, severity and monitoring of IBD is largely based on the combined effects of clinical presentations, endoscopy, radiology, histology and laboratory biomarkers. Some laboratory biomarkers of IBD such as C–reactive protein (CRP), erythrocyte sedimentation rate (ESR), platelets etc are associated with systemic and gastrointestinal inflammation or disease activity, i.e., active or quiescent IBD. Others are linked to genetic predisposition, e.g., autophagy genes, nucleotide–binding oligomerization domain–containing protein 2 (NOD2), interleukin–23 receptor (IL23R) etc, correlated with the neoplastic transformation, e.g., M2–pyruvate kinase, miRNAs, mucosal chitinase–3–like protein 1 (CH13L1) etc, and coupled to drug metabolism in relation to therapeutic intervention e.g., Thiopurine Methyltransferase (TPMT) and 6–Thioguanine Nucleotide (6TGN). There are also those such as anti–neutrophil cytoplasmic antibodies (ANCAs), and anti–saccharomyces cerevisiae antibodies (ASCAs) that are related to the type of IBD, i.e., either CD, UC or IBDU. This review summarises the characterisation of laboratory biomarkers of IBD including a narrative on their future perspectives from the standpoint of diagnosis, prognosis, monitoring the disease course and a practical algorithm for the practical application of these biomarkers in the assessment of IBD.