From the Guidelines
Positive lactoferrin suggests active intestinal inflammation, most commonly associated with inflammatory bowel disease (IBD) such as Crohn's disease or ulcerative colitis, with a sensitivity of 83% and specificity of 75% for detecting endoscopic inflammation 1. This finding is clinically significant as lactoferrin is a protein released by neutrophils during inflammation, making it a reliable biomarker for distinguishing inflammatory from non-inflammatory gastrointestinal conditions. When lactoferrin is detected in stool samples, it indicates neutrophil presence in the intestinal mucosa, which doesn't occur in functional disorders like irritable bowel syndrome (IBS). Some key points to consider include:
- The diagnostic performance of fecal lactoferrin for detecting moderate to severe endoscopic inflammation has been reported in several studies, with a commercial assay cutoff of 7.25 mg/g 1.
- Positive results should prompt further diagnostic evaluation, including colonoscopy with biopsies, imaging studies, and other inflammatory markers like C-reactive protein and erythrocyte sedimentation rate.
- The level of lactoferrin can also help monitor disease activity and treatment response in patients with established IBD.
- However, false positives can occur with infections, certain medications, or bleeding, so clinical correlation is essential for proper interpretation.
- A threshold value in the range of 4.0–7.25 mg/g for fecal lactoferrin is recommended to optimize sensitivity for IBD, although this may not be the only factor to consider in clinical practice 1.
From the Research
Positive Lactoferrin Test Results
A positive lactoferrin test suggests the presence of an inflammatory condition in the colon, such as:
- Ulcerative colitis
- Crohn's disease
- Ischemic colitis
- Microscopic colitis
- Inflammatory bowel disease (IBD) 2, 3
Diagnostic Accuracy
The sensitivity, specificity, and positive and negative predictive values of the fecal lactoferrin test for ulcerative or Crohn's colitis are:
- Sensitivity: 90%
- Specificity: 98%
- Positive predictive value: 82%
- Negative predictive value: 99% 2
Clinical Significance
Elevated lactoferrin levels are associated with:
- Inflammatory disease activity
- Mucosal healing and histologic improvement
- Postoperative recurrence risk
- Pouchitis prediction 3
- Correlation with markers of inflammation, such as CRP, and stool frequency 4
Immunomodulatory and Antimicrobial Role
Lactoferrin has been shown to have:
- Immunomodulatory and anti-inflammatory activities
- Antimicrobial properties against bacteria and viruses, including SARS-CoV-2 5