What is the next step in managing a patient with elevated fecal calprotectin and a negative stool occult blood test?

Management of Elevated Fecal Calprotectin (73.7 μg/g) with Negative Stool Occult Blood

With a fecal calprotectin of 73.7 μg/g (above the 50 μg/g threshold but below 150 μg/g) and negative occult blood, you should proceed with colonoscopy to evaluate for inflammatory bowel disease, as this intermediate level carries an 8% risk of IBD over 12 months. 1

Risk Stratification Based on Calprotectin Level

Your patient's calprotectin of 73.7 μg/g falls into the "indeterminate range" (50-249 μg/g), which requires careful clinical assessment:

• Calprotectin >50 μg/g indicates IBD is more likely than IBS, making further investigation necessary 1
• The 8% IBD risk at 12 months for this range is significantly higher than the 1% risk seen with levels <50 μg/g 1
• Levels >150 μg/g would strongly suggest active inflammation, but your patient's level doesn't reach this threshold 1

Recommended Next Steps

Primary Action: Colonoscopy with Biopsies

Proceed with colonoscopy and obtain multiple biopsies from different colonic segments and terminal ileum 1

• The British Society of Gastroenterology recommends colonoscopy as the definitive investigation for chronic diarrhea when calprotectin is elevated above 50 μg/g 1
• Biopsies are essential even if mucosa appears normal endoscopically, as histologic inflammation can exist without visible endoscopic changes 2

Alternative Approach: Repeat Calprotectin Testing

If immediate colonoscopy is not feasible or the patient prefers to wait:

• Repeat fecal calprotectin in 3-6 months to assess trajectory 1, 3
• The York Faecal Calprotectin Care Pathway found that 53% of patients with elevated calprotectin showed reduction on repeat testing after a median of 18 days 1
• If calprotectin rises above 150 μg/g or symptoms worsen, colonoscopy becomes mandatory 1

Critical Clinical Context Needed

Assess for Red Flag Symptoms

Do not rely on calprotectin alone if any of the following are present:

• Rectal bleeding, abdominal pain, change in bowel habit, weight loss, or iron-deficiency anemia require cancer pathway referral regardless of calprotectin level 1, 4
• Calprotectin is not sensitive enough to exclude colorectal cancer or advanced adenomas 1, 4
• Age >40 years with new-onset symptoms warrants colonoscopy regardless of calprotectin 1

Rule Out Other Causes of Elevated Calprotectin

Before attributing the elevation to IBD, exclude:

• Infectious gastroenteritis - obtain stool culture and consider C. difficile testing 1, 5
• NSAID use - calprotectin rises with NSAID-induced enteropathy 1, 5
• Celiac disease - check tissue transglutaminase antibodies 1

Interpretation of Negative Occult Blood

The negative occult blood test does not exclude IBD or reduce the need for colonoscopy:

• Occult blood testing has different diagnostic utility than calprotectin - it primarily screens for colorectal cancer 1
• IBD can present with elevated calprotectin but negative occult blood, particularly in mild or patchy disease 1
• The combination doesn't change the 8% IBD risk associated with your patient's calprotectin level 1

Common Pitfalls to Avoid

• Don't assume IBS based on intermediate calprotectin alone - the 8% IBD risk mandates investigation 1
• Don't use calprotectin cutoffs >250 μg/g as the sole trigger for colonoscopy - the British Society of Gastroenterology uses 50 μg/g as the decision threshold 1
• Don't delay colonoscopy if symptoms are severe or progressive, even with intermediate calprotectin 1
• Don't order empiric IBD treatment without endoscopic confirmation when calprotectin is in the intermediate range 1, 3

Monitoring Strategy if Colonoscopy is Delayed

If you choose repeat calprotectin testing first:

• Recheck in 3-6 months maximum 1, 3
• Proceed immediately to colonoscopy if: calprotectin rises, symptoms worsen, or red flag features develop 1
• Consider FIT (fecal immunochemical test) if age >40 years to assess colorectal cancer risk while awaiting colonoscopy 1