Faecal Calprotectin: A Non-Invasive Marker for Diagnosing and Monitoring Acute Diverticulitis

Acute diverticulitis (AD) is a prevalent gastrointestinal disorder with a significant recurrence rate. Faecal calprotectin (FC) is a non-invasive biomarker of intestinal inflammation, but its role in diagnosing and monitoring diverticulitis remains to be fully established.

This narrative review aims to evaluate the current evidence on the utility of FC in the diagnosis, severity assessment, prediction of recurrence, and monitoring of therapeutic response in patients with diverticular disease (DD) and AD.

A structured literature search was conducted using PubMed, Scopus, and ScienceDirect for peer-reviewed original studies published in English between 2004 and April 2025. The search strategy combined terms related to diverticular disease and faecal calprotectin. Studies reporting original data on FC in DD were synthesised narratively.

FC demonstrates significant utility across multiple clinical applications in DD. For diagnosis, FC is markedly elevated in AD (mean 556-695 μg/g) and symptomatic uncomplicated diverticular disease (SUDD) (median 181 μg/g), while remaining normal in irritable bowel syndrome (mean 50 μg/g), enabling differentiation between organic and functional disorders. FC correlates strongly with endoscopic disease severity, with positivity rates increasing from 48.6% in DICA 1 to 93.2% in DICA 3 (p < 0.0001). For predicting recurrence, elevated FC identifies patients at high risk, with one study reporting 87.5% of recurrent cases showing prior FC elevation and a negative predictive value of 96.8%. FC also exhibits excellent short-term prognostic capacity (AUC 0.976 at 3 months) and responds to therapeutic intervention, with significant reductions following successful treatment with probiotics, nutraceuticals, budesonide, and other agents.

FC is a promising non-invasive biomarker for diagnosing diverticulitis, assessing disease severity, predicting recurrence, and monitoring treatment response. Its ability to detect subclinical inflammation makes it particularly useful for risk stratification. However, the current evidence base consists predominantly of retrospective and observational studies, and standardised thresholds require further validation through prospective trials before routine clinical implementation can be recommended.