Management of Intermittent Diarrhea with Calprotectin 185 μg/g
Proceed directly to colonoscopy with terminal ileum intubation and obtain biopsies to establish a diagnosis, as a calprotectin of 185 μg/g indicates active intestinal inflammation that requires endoscopic evaluation to guide treatment. 1, 2
Diagnostic Approach
Immediate Endoscopic Evaluation
Complete colonoscopy with terminal ileum intubation is the next step, as calprotectin >150 μg/g strongly suggests active inflammatory disease requiring visualization and tissue diagnosis 1, 2
Obtain multiple biopsies even from normal-appearing mucosa to establish histologic diagnosis, as symptom severity may not correlate with endoscopic findings 1, 2
Early endoscopy (within 7-30 days of symptom onset) is associated with significantly shorter symptom duration (19 vs 47 days) and reduced steroid treatment duration compared to delayed endoscopy 1
Pre-Endoscopy Workup
Before colonoscopy, complete the following:
Stool studies for infectious causes including bacterial culture, ova and parasites, and C. difficile testing, as elevated calprotectin is not specific for IBD and can occur with gastrointestinal infections 2, 3
Complete blood count, CRP, ESR, and comprehensive metabolic panel to assess systemic inflammation and rule out complications 2
Consider cross-sectional imaging (MR or CT enterography) if Crohn's disease is suspected based on symptoms or initial findings, to evaluate small bowel involvement 2
Interpretation of Calprotectin 185 μg/g
Clinical Significance
This level (>150 μg/g) has 90.6% sensitivity for detecting endoscopically active disease and strongly indicates organic intestinal inflammation rather than functional symptoms 2, 4
At this threshold, specificity improves significantly compared to lower cutoffs, making false positives less likely in symptomatic patients 1, 2
The positive predictive value is high in symptomatic patients, with only 4.6% false positive rate in those with moderate-to-severe symptoms 2
Differential Considerations
While elevated calprotectin strongly suggests IBD, other causes must be excluded:
Colorectal neoplasia can elevate calprotectin, making endoscopy essential regardless 2
NSAID use within the past 6 weeks can affect calprotectin levels and should be documented 5, 6
Gastrointestinal infections must be ruled out with stool studies before attributing symptoms solely to IBD 2, 3
Common Pitfalls to Avoid
Do Not Delay Endoscopy
Do not treat empirically without tissue diagnosis in a patient with new-onset symptoms and elevated calprotectin, as the underlying etiology must be established 1, 2
Do not assume IBS based on intermittent symptoms alone, as 21-25% of IBD patients in remission can have coexisting IBS-like symptoms with elevated calprotectin indicating subclinical inflammation 7, 8
Do Not Rely on Symptoms Alone
Symptom severity does not reliably correlate with endoscopic or histologic inflammation severity, making objective assessment with endoscopy essential 1
Intermittent symptoms do not rule out significant inflammation, as calprotectin provides objective evidence of ongoing intestinal inflammation independent of symptom pattern 8
Post-Endoscopy Management
If IBD is Confirmed
Treatment decisions should be based on endoscopic and histologic severity, not just symptoms or calprotectin level 1
Serial calprotectin monitoring at 3-6 month intervals can facilitate early recognition of disease flares once diagnosis is established 2
Target calprotectin <50 μg/g as a marker of mucosal healing during maintenance therapy 2
If Endoscopy is Normal
Consider celiac disease testing, as this is a common cause of false-negative endoscopy with elevated calprotectin 6
Reassess medication history for NSAIDs or aspirin use that may cause subclinical inflammation 6
Consider small bowel imaging if Crohn's disease remains suspected despite normal colonoscopy 2