What are the next steps for a patient with a Fecal Calprotectin result of 128 ug/g, indicating Inflammatory Bowel Disease (IBD)?

Management of Fecal Calprotectin 128 μg/g

A patient with fecal calprotectin of 128 μg/g falls in the intermediate range (100-250 μg/g) and should either undergo repeat calprotectin testing or be referred to gastroenterology for further evaluation, with the decision based on clinical suspicion of IBD and symptom severity. 1

Interpretation of This Result

• Your calprotectin level of 128 μg/g indicates possible intestinal inflammation but is not definitively diagnostic of active IBD, as this intermediate range (100-250 μg/g) requires clinical correlation. 1

• At this level, the test has moderate specificity (66%) for detecting active endoscopic inflammation, meaning there is a meaningful false-positive rate that necessitates further investigation. 1

• The British Society of Gastroenterology specifically addresses this intermediate range, stating that calprotectin should be interpreted in light of pre-test probability of IBD based on clinical features and family history. 1

Immediate Next Steps Based on Clinical Context

If You Have Moderate to Severe Symptoms (rectal bleeding, significant abdominal pain, weight loss, frequent diarrhea):

• Proceed directly to urgent gastroenterology referral for colonoscopy evaluation, as the combination of moderate-to-severe symptoms with calprotectin >100 μg/g warrants endoscopic assessment. 1

• Do not delay referral for repeat testing in this scenario, as symptomatic patients with elevated calprotectin require direct visualization of the bowel. 2, 3

If You Have Mild or Minimal Symptoms:

• Consider repeat calprotectin testing after 2-3 weeks to determine if the elevation is persistent or transient. 1

• In the York Faecal Calprotectin Care Pathway evaluation, 53% of patients with initial calprotectin ≥100 μg/g showed reduction on repeat testing, either to <100 μg/g or remaining in the intermediate range. 1

• If repeat testing shows calprotectin <100 μg/g and symptoms are consistent with IBS, treat as IBS in primary care. 1

• If repeat testing shows persistent elevation (>100 μg/g) or calprotectin increases to >250 μg/g, proceed to routine or urgent gastroenterology referral respectively. 1

If You Are Asymptomatic or Have Known IBD:

• If you have established IBD and are currently asymptomatic, a calprotectin of 128 μg/g suggests subclinical inflammation that may predict future relapse, warranting consideration of endoscopic assessment or treatment optimization. 1, 3

• In known IBD patients, calprotectin >100 μg/g correlates with endoscopic activity and may guide treatment escalation decisions. 1

Essential Baseline Testing Required

Before or concurrent with gastroenterology referral, the following tests should be completed in primary care:

• Complete blood count (to assess for anemia, thrombocytosis indicating inflammation). 1

• Urea and electrolytes (to assess for dehydration, electrolyte abnormalities). 1

• C-reactive protein (CRP) (complementary inflammatory marker, though 20% of active Crohn's patients may have normal CRP). 1

• Coeliac screen (tissue transglutaminase antibodies to exclude celiac disease). 1

• Stool culture (to exclude infectious causes of inflammation, as gastroenteritis can also elevate calprotectin). 1

• Liver function tests and albumin (to assess nutritional status and exclude hepatobiliary involvement). 1

Important Caveats for Interpretation

• NSAID use within the past 6 weeks can falsely elevate calprotectin and should be documented; if present, repeat testing after NSAID cessation is appropriate. 1

• Calprotectin is not specific for IBD and can be elevated in infectious gastroenteritis, colorectal cancer, microscopic colitis, and other inflammatory conditions. 1, 3

• If you have alarm features (rectal bleeding with abdominal pain, change in bowel habit, weight loss, or iron-deficiency anemia), you should be referred via a suspected cancer pathway regardless of calprotectin level, as calprotectin is not sensitive enough to exclude colorectal cancer. 1

• Disease location affects test performance: Calprotectin may be modestly less accurate in detecting small bowel Crohn's disease compared to colonic disease, though this should not prevent its use. 1

• Assay variability exists: Different calprotectin assays may not be interchangeable, and there can be substantial within-day variation in measurements from a single patient. 1

Timing Considerations

• If repeat testing is chosen, obtain the first stool sample of the morning and ensure it is analyzed within 3 days if stored at room temperature. 1, 3

• If symptoms worsen or new alarm features develop while awaiting repeat testing or gastroenterology appointment, proceed immediately to urgent evaluation. 1

• Patients should be admitted for urgent inpatient assessment if systemically unwell or if acute severe colitis is suspected (≥6 bloody stools per day with systemic toxicity). 1

What Gastroenterology Evaluation Will Entail

• Ileocolonoscopy with biopsies is the gold standard for diagnosing IBD, assessing disease extent, severity, and differentiating Crohn's disease from ulcerative colitis. 1

• Cross-sectional imaging (MRI or CT enterography) may be needed to assess small bowel involvement and complications such as strictures, fistulas, or abscesses. 1

• Endoscopic findings will be correlated with your calprotectin level to establish baseline values for future monitoring. 1