What blood tests are used to diagnose Inflammatory Bowel Disease (IBD)?

From the Guidelines

Blood tests, including complete blood count, C-reactive protein, erythrocyte sedimentation rate, serum electrolytes, liver enzymes, serum albumin, and renal function, should be performed in patients with suspected inflammatory bowel disease (IBD) to assess disease activity and rule out complications, as recommended by the most recent guidelines 1. When evaluating patients with suspected IBD, it is essential to use a combination of diagnostic modalities, including clinical, biochemical, endoscopic, radiological, and histological diagnostics, rather than relying on a single reference standard 1. The diagnosis of IBD typically involves a combination of blood tests, stool tests, imaging studies, and endoscopic procedures with biopsies. Some of the key blood tests used in the evaluation of suspected IBD include:

• Complete blood count (CBC) to check for anemia and elevated white blood cell count
• C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) to measure inflammation
• Comprehensive metabolic panel to assess liver and kidney function
• Serologic markers like anti-Saccharomyces cerevisiae antibodies (ASCA) and perinuclear anti-neutrophil cytoplasmic antibodies (pANCA) to help differentiate between Crohn's disease and ulcerative colitis It is also crucial to rule out infectious causes, especially Clostridium difficile and Cytomegalovirus, in patients with suspected IBD flare 1. Fecal calprotectin, a highly sensitive stool marker for intestinal inflammation, can be useful in assessing disease activity, but it is not a blood test 1. Overall, while blood tests are essential in the evaluation of suspected IBD, they should be used in conjunction with other diagnostic modalities to confirm the diagnosis and guide treatment decisions.

From the Research

Blood Tests for Inflammatory Bowel Disease

• Blood tests can be used to monitor inflammatory bowel disease (IBD) and predict complications 2, 3, 4, 5, 6
• Common blood parameters used to monitor IBD include:
  • C-reactive protein (CRP) 3, 4, 5, 6
  • Erythrocyte sedimentation rate (ESR) 3, 4, 6
  • Total white blood cell (WBC) count 6
  • Eosinophil (EOS) count 6
  • Platelet (PLT) count 6

Correlation with Disease Activity

• CRP and ESR values can correlate with disease activity in Crohn's disease, but not always in ulcerative colitis 3
• Higher serum CRP levels and total WBC counts can indicate a higher hazard for pseudopolyp formation in ulcerative colitis patients 6
• Higher serum ESR and lower eosinophil count can predict the development of fistulas in Crohn's disease patients 6
• Higher serum ESR and PLT counts can account for strictures in Crohn's disease patients 6

Prediction of Complications

• Routine blood parameters at diagnosis can be used to predict complications in IBD patients 6
• A dual parameter prediction system can be constructed using CRP level, ESR, WBC count, PLT, and eosinophils to predict complications in IBD 6