From the Guidelines
To assess Crohn's disease activity, laboratory tests such as a full blood count, serum C-reactive protein level, erythrocyte sedimentation rate, serum electrolytes, liver enzymes level, serum albumin, renal function, and fecal calprotectin level should be performed, as recommended by the WSES-AAST guidelines 1. When evaluating Crohn's disease, it is essential to consider the patient's clinical symptoms and medical history. The laboratory tests recommended by the WSES-AAST guidelines 1 provide a comprehensive assessment of disease activity and help guide treatment decisions.
- Key laboratory tests include:
- Full blood count to check for anemia, leukocytosis, and thrombocytosis
- Serum C-reactive protein level and erythrocyte sedimentation rate to measure inflammation
- Serum electrolytes, liver enzymes level, and renal function to assess organ function
- Serum albumin to evaluate nutritional status
- Fecal calprotectin level to detect intestinal inflammation Additionally, it is crucial to exclude infectious diseases by performing blood, stool cultures, and toxin test for Clostridium difficile, as recommended by the WSES-AAST guidelines 1. The results of these laboratory tests should be interpreted in conjunction with clinical symptoms and imaging studies to provide a comprehensive assessment of Crohn's disease activity and guide treatment decisions.
From the Research
Labs to Assess Crohn's Disease
To assess Crohn's disease, several laboratory tests can be used, including:
- C-reactive protein (CRP) levels: Elevated CRP levels are associated with increased disease activity in Crohn's disease 2, 3, 4
- Erythrocyte sedimentation rate (ESR): ESR is also higher in Crohn's disease, but it does not closely reflect disease activity in individual patients 2
- Fecal calprotectin: Measurement of fecal calprotectin has value to rule out disease in adults and children 5
- Blood tests: Such as complete blood count, liver function tests, and electrolyte panels to monitor for complications and side effects of treatment 5
Correlation between CRP Levels and Disease Activity
Studies have shown a correlation between CRP levels and disease activity in Crohn's disease:
- A study found that CRP levels were significantly higher in Crohn's disease than in ulcerative colitis, and that CRP levels corresponded closely with clinical and pathological indices of relapse, remission, and response to therapy 2
- Another study found that the optimal CRP threshold value to separate patients with moderate to severe disease from others was 19mg/L, with a sensitivity of 76.4% and a specificity of 56.2% 3
- Elevated CRP levels were also found to be associated with an increased risk of complications, such as penetrating complications and osteoporosis 6, 5
Selection of Patients for Further Testing
To optimize the selection of patients for further testing, such as capsule enteroscopy, the following factors can be considered:
- Biochemical profile: Elevated CRP levels and low serum iron were found to be associated with an increased risk of Crohn's disease 4
- Clinical presentation: Symptoms such as diarrhea, abdominal pain, rectal bleeding, fever, weight loss, and fatigue can indicate the presence of Crohn's disease 5
- Risk factors: Such as family history, smoking, and environmental factors can increase the risk of developing Crohn's disease 5