Fecal Lactoferrin Test

Fecal lactoferrin is a protein released by neutrophils, which are white blood cells that respond rapidly to injury or infection. When the intestinal lining becomes inflamed, neutrophils move into the gut lumen and release lactoferrin. Because this protein stays stable as it passes through the digestive tract, it serves as a reliable marker of true intestinal inflammation. This makes fecal lactoferrin particularly useful in chronic conditions such as inflammatory bowel disease. In ulcerative colitis and Crohn’s disease, the immune system mounts a sustained inflammatory response in the intestine, and fecal lactoferrin levels tend to rise in parallel with the severity of this inflammation.

Lactoferrin helps distinguish inflammatory conditions from non-inflammatory ones. For example, irritable bowel syndrome creates abdominal discomfort but does not trigger neutrophil activity, so lactoferrin levels typically remain low. That said, infections such as Clostridioides difficile or acute bacterial enteritis can also raise lactoferrin, so interpretation always requires clinical context. Levels also tend to correlate more strongly with colonic inflammation than with inflammation isolated to the small bowel because the colon contains a higher density of neutrophils and sheds more detectable protein.

Fecal lactoferrin levels often mirror what a gastroenterologist might see on endoscopy or microscopic tissue evaluation. As inflammation worsens, lactoferrin rises; as inflammation resolves with therapy and mucosal healing, lactoferrin declines. Because of this tight correlation, many clinicians use serial measurements to track treatment response or to anticipate disease flares. This can reduce the need for repeat colonoscopies, which are invasive and costly. In pediatric inflammatory bowel disease, where minimizing procedures is especially important, lactoferrin is particularly valuable.

Although fecal lactoferrin performs similarly to fecal calprotectin in many settings, some evidence suggests that lactoferrin may be slightly better at detecting active inflammation in ulcerative colitis. In Crohn’s disease, the two markers are generally comparable. As with all biomarkers, lactoferrin is not perfect: small bowel-predominant Crohn’s disease may produce lower-than-expected values, and differences in laboratory cutoffs can influence interpretation. Still, when integrated with symptoms, imaging, and endoscopy, fecal lactoferrin remains a sensitive, specific, and noninvasive tool for assessing real inflammatory activity in the gut.