Endoscopic Assessment is the Priority for This Patient
This patient with 2 weeks of persistent diarrhea, negative infectious workup, and elevated fecal lactoferrin (177.44 μg/g) requires endoscopic evaluation to identify the underlying inflammatory cause before initiating treatment. 1, 2, 3
Rationale for Endoscopy
The elevated lactoferrin level indicates intestinal inflammation with high specificity:
- Fecal lactoferrin has 90% specificity for identifying active inflammation in inflammatory bowel disease (IBD), with 90% sensitivity for detecting histologic inflammation on biopsy. 4, 5
- In patients with chronic diarrhea and positive lactoferrin, the major underlying cause is chronic inflammatory bowel disease of the colon, with a positive predictive value of 82% for ulcerative colitis or Crohn's disease. 5
- Early endoscopy (within 2 weeks of symptom onset) is strongly recommended for all patients with positive lactoferrin results, as it leads to shorter symptom duration (19 vs 47 days), shorter steroid treatment duration (49 vs 74 days), and reduced symptom recurrence (21.8% vs 50%). 1
Diagnostic Approach
Proceed with colonoscopy and consider upper endoscopy with biopsies:
- The AGA recommends endoscopic assessment rather than empiric treatment when inflammatory biomarkers are elevated, even in patients with mild symptoms. 1
- Obtain biopsies even from normal-appearing mucosa, as lactoferrin can detect microscopic inflammation before it becomes visually apparent on endoscopy. 2
- If initial colonoscopy is unrevealing but lactoferrin remains elevated, consider capsule endoscopy to evaluate the small bowel for Crohn's disease, as standard endoscopy can miss subtle mucosal inflammation. 2
Management Based on Endoscopic Findings
If Endoscopy Confirms IBD:
- Initiate treatment based on disease severity and distribution found on endoscopy and histology. 1
- For ulcerative colitis with moderate to severe inflammation (Mayo Endoscopic Score 2-3), consider biologic therapy rather than mesalamine alone. 6
- Monitor treatment response with repeat fecal lactoferrin in 2-4 months and endoscopy at 6-12 months to confirm mucosal healing. 2, 7
If Endoscopy Shows No Inflammation:
- Consider other causes of elevated lactoferrin including NSAIDs (if used within past 6 weeks), microscopic colitis (requires biopsies), or segmental disease missed by standard endoscopy. 3
- Repeat lactoferrin measurement in 3-6 months to confirm normalization. 2, 3
- If lactoferrin remains elevated on repeat testing despite negative endoscopy, proceed with capsule endoscopy or consider biopsies from previously normal-appearing areas. 2
Critical Caveats
Do not initiate empiric corticosteroid or immunosuppressive therapy without endoscopic confirmation of inflammation, as this approach delays accurate diagnosis and may obscure endoscopic findings if performed later. 1
The 2-week duration of symptoms makes infectious causes less likely despite the negative stool cultures, but the elevated lactoferrin strongly suggests an inflammatory rather than functional etiology (lactoferrin is 100% specific in ruling out irritable bowel syndrome). 4, 5