Management of Ulcerative Proctitis with Markedly Elevated Fecal Calprotectin

Diagnostic Work‑up

• Perform flexible sigmoidoscopy or colonoscopy with segmental biopsies to confirm ulcerative proctitis, define disease extent, and obtain histology. 1, 2
• Colonoscopy is preferred initially because approximately 50 % of patients presenting with isolated proctitis later develop more extensive disease. 3
• Segmental biopsies throughout the colon are required; endoscopic appearance alone may underestimate true disease extent, especially when inflammation is quiescent. 3
• Exclude infectious etiologies (e.g., Clostridioides difficile and other enteric pathogens) before attributing symptoms to inflammatory bowel disease, as infections can raise fecal calprotectin and mimic IBD. 4, 5
• Obtain baseline laboratory studies (complete blood count, C‑reactive protein, albumin, erythrocyte sedimentation rate) to assess systemic inflammation and identify severe disease. 1, 3

Initial (First‑Line) Therapy

• Initiate mesalamine 1 g rectal suppository once daily as the preferred first‑line treatment for mild‑to‑moderate proctitis. 1
• Rectal suppositories are superior to enemas or foam formulations for targeting rectal inflammation and are better tolerated. 1
• Topical mesalamine is more effective than topical corticosteroids for inducing remission in proctitis. 1
• No additional clinical benefit is observed with doses >1 g daily for topical mesalamine. 1

Combination Therapy for Enhanced Efficacy

• Consider adding oral mesalamine (or topical steroids if needed) to the rectal suppository; combination therapy yields higher remission rates than monotherapy. 1
• This approach is especially appropriate when fecal calprotectin is markedly elevated (>150 mg/g), indicating significant mucosal inflammation. 4

Monitoring Strategy

Short‑Term (First 3 Months)

• Measure fecal calprotectin to evaluate treatment response; a reduction to <50 mg/g is preferred for confirming endoscopic improvement (Mayo Endoscopic Score 0‑1). 4

Endoscopic Reassessment

• Perform endoscopic evaluation (flexible sigmoidoscopy) 3–6 months after therapy initiation to document mucosal healing. 2
• Flexible sigmoidoscopy is sufficient for most ulcerative colitis patients to assess disease activity. 2

Long‑Term Monitoring

• In patients achieving clinical remission, conduct proactive monitoring every 6–12 months using patient‑reported outcomes together with objective markers (fecal calprotectin and CRP). 6
• If fecal calprotectin remains >150 mg/g despite symptomatic remission, schedule endoscopic assessment rather than empiric medication changes. 4, 5
• Alternatively, repeat fecal calprotectin in 3–6 months may be reasonable before proceeding to endoscopy. 4

Escalation for Refractory Disease

• If symptoms persist after 8–12 weeks of optimized topical and oral mesalamine, escalate therapy to systemic corticosteroids, immunosuppressants, or biologic agents. 1

Prognosis and Clinical Pitfalls

• Up to 50 % of patients initially diagnosed with isolated proctitis will develop more extensive disease over time, and about 10 % will progress to extensive colitis; therefore, initial colonoscopy with biopsies is essential to establish true disease extent. 3
• Do not rely solely on fecal calprotectin for monitoring proctitis, as its correlation with endoscopic findings is weaker than in more extensive disease; endoscopic confirmation remains important for treatment decisions. [ignored refs omitted]
• Do not delay escalation to advanced therapies in truly refractory proctitis, as refractory disease can significantly impair quality of life and may require biologic treatment. 1

Diagnostic Accuracy and Interpretation of a Fecal Calprotectin Level of ≈ 190 µg/g

Diagnostic Performance Metrics

• In patients with a fecal calprotectin of ≈ 190 µg/g (above the 150 µg/g threshold), the test shows 71 % sensitivity and 69 % specificity for detecting moderate‑to‑severe endoscopic inflammation. 7

Interpretation of Thresholds

• A fecal calprotectin value of ≈ 190 µg/g lies between the 150 µg/g and 250 µg/g cut‑offs recommended in current inflammatory bowel disease (IBD) guidelines for distinguishing active disease from functional disorders. [7][8]
• At the 150 µg/g threshold, the false‑negative rate is about 4.3 %, meaning that roughly 4 out of 100 patients with moderate‑to‑severe endoscopic activity could be incorrectly reassured by a lower calprotectin result. 7