What laboratory tests should be ordered for the diagnosis of Inflammatory Bowel Disease (IBD)?

From the Guidelines

For diagnosing inflammatory bowel disease (IBD), a comprehensive laboratory workup should include complete blood count (CBC), comprehensive metabolic panel, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), fecal calprotectin, and stool studies to rule out infectious causes, as recommended by the most recent guidelines 1. When evaluating patients with suspected IBD, it is essential to consider the combination of clinical presentation, laboratory tests, and imaging studies to establish an accurate diagnosis.

• The laboratory workup should include:
  • Complete blood count (CBC) to assess for anemia and leukocytosis
  • Comprehensive metabolic panel to evaluate liver function and nutritional status
  • CRP and ESR as inflammatory markers
  • Fecal calprotectin, which is highly sensitive for intestinal inflammation
  • Stool studies to rule out infectious causes, such as Clostridium difficile toxin testing
• Additional tests may include iron studies, vitamin B12 and folate levels to assess malabsorption, and perinuclear anti-neutrophil cytoplasmic antibodies (p-ANCA) and anti-Saccharomyces cerevisiae antibodies (ASCA) to help differentiate between ulcerative colitis and Crohn's disease, as suggested by previous studies 1. The most recent guidelines 1 emphasize the importance of assessing disease activity in the urgent clinical situation by performing laboratory tests, including full blood count, serum C-reactive protein level, erythrocyte sedimentation rate level, serum electrolytes, liver enzymes level, serum albumin, renal function, and faecal calprotectin level, when possible. It is also crucial to exclude any infectious diseases by performing blood, stool cultures, and toxin tests for Clostridium difficile, as recommended by the guidelines 1. These laboratory tests complement the clinical evaluation and imaging studies but are not definitive on their own; endoscopy with biopsy remains the gold standard for IBD diagnosis, as noted in various studies 1.

From the Research

Laboratory Tests for IBD Diagnosis

The following laboratory tests can be ordered for the diagnosis of Inflammatory Bowel Disease (IBD):

• C-reactive protein (CRP) 2, 3
• Erythrocyte sedimentation rate (ESR) 2, 3
• Fecal calprotectin 2
• Fecal lactoferrin 2
• Complete blood count (CBC) parameters, such as platelet to lymphocyte ratio (PLR), red blood cell distribution width (RDW), and neutrophil to lymphocyte ratio (NLR) 3
• Albumin (ALB) levels 3
• C-reactive protein/albumin ratio (CRP/ALB) 3

Disease Activity Assessment

These laboratory tests can also be used to assess disease activity in IBD patients:

• CRP/ALB ratio 3
• CRP levels 2, 3
• ESR 2, 3
• Fecal calprotectin 2
• CBC parameters, such as PLR, RDW, and NLR 3

Additional Tests

Other tests that may be useful in the diagnosis and management of IBD include:

• Endoscopy and biopsy 4, 5
• Histology 4, 5
• Imaging studies, such as radiologic examinations 4, 5
• Therapeutic drug monitoring (TDM) 6
• Surveillance for infectious complications, such as tuberculosis or hepatitis B virus 6
• Detection of nutritional deficiencies, such as vitamin B12 deficiency 6