Management of Subacute Diarrhea with Mildly Elevated Fecal Calprotectin in a 70-Year-Old Male
For a 70-year-old male with subacute diarrhea and mildly elevated fecal calprotectin of 72 μg/g, the most appropriate management approach is to pursue additional diagnostic testing including stool studies for infection, blood tests, and consideration of colonoscopy to rule out inflammatory or malignant conditions. 1
Significance of Fecal Calprotectin Level
A fecal calprotectin level of 72 μg/g is mildly elevated above the normal reference range (typically <50 μg/g) but falls below the threshold that would strongly suggest inflammatory bowel disease:
- Values <50 μg/g are considered normal
- Values between 50-100 μg/g represent mild elevation
- Values between 100-250 μg/g are considered intermediate
- Values >250 μg/g strongly suggest active inflammation 1
The British Society of Gastroenterology guidelines indicate that while a normal calprotectin has a high negative predictive value for IBD, mildly elevated levels have a low positive predictive value and require careful interpretation in clinical context 1.
Diagnostic Algorithm
Step 1: Initial Assessment
- Complete blood count, C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR)
- Comprehensive stool studies:
- Celiac serology
Step 2: Evaluate for Red Flags
Given the patient's age (70 years) and presentation, be vigilant for concerning features:
- Weight loss
- Rectal bleeding
- Nocturnal symptoms
- Family history of colorectal cancer 1
Step 3: Management Decision Based on Findings
If infectious etiology identified:
- Treat specific infection according to pathogen identified
- Consider antimicrobial therapy only if indicated by specific pathogen 1
- Provide supportive care with oral rehydration
If no infectious etiology and symptoms persist:
- Proceed with colonoscopy - this is particularly important in a 70-year-old male with new-onset diarrhea, even with only mildly elevated calprotectin 3, 4
- Colonoscopy is warranted to exclude:
- Inflammatory bowel disease
- Microscopic colitis (common in older adults)
- Colorectal malignancy
- Ischemic colitis 1
Supportive Management During Diagnostic Workup
- Maintain hydration with oral rehydration solutions (200-400 mL after each loose stool) 2
- Consider BRAT diet (bananas, rice, applesauce, toast) 2
- Avoid lactose-containing products, alcohol, caffeine, and spicy foods 2
- Antimotility agents (loperamide 4 mg initially, then 2 mg after each loose stool, maximum 16 mg/day) may be used if no fever or bloody stools 2
Important Considerations
Age is a critical factor: In a 70-year-old with new-onset diarrhea, colorectal cancer must be excluded, even with only mildly elevated calprotectin 3
Calprotectin interpretation: A level of 72 μg/g is only mildly elevated and could be associated with:
Medication review: Assess for medications that could cause diarrhea or affect calprotectin levels (PPIs, NSAIDs, antibiotics) 1
Repeat testing: If initial workup is negative but symptoms persist, consider repeating calprotectin measurement after 2-3 weeks to assess trend 1
Common Pitfalls to Avoid
Don't assume IBS in older adults with new-onset symptoms - organic causes are more common in this age group
Don't rely solely on calprotectin level - a value of 72 μg/g is in a gray zone and requires clinical correlation 1
Don't miss colorectal cancer - studies have shown elevated calprotectin in some cases of colorectal malignancy 3, 4
Don't automatically attribute symptoms to IBD - in acute/subacute diarrhea, infectious causes must be excluded first 6
Don't delay colonoscopy in an older adult with persistent symptoms - early endoscopic evaluation is warranted in this age group regardless of calprotectin level 1