Lactoferrin is a glycoprotein expressed by activated neutrophils. The detection of lactoferrin in a fecal sample therefore serves as a surrogate marker for inflammatory white blood cells (WBCs) in the intestinal tract. WBCs in the stool are not stable and may be easily destroyed by temperature changes, delays in testing, and toxins within the stool. As a result, WBCs may not be detected by common microscopic methods. Lactoferrin assay has allowed the identification of inflammatory cells in the stool without the use of microscopy.
Lactoferrin test is used to diagnose inflammatory bowel diseases such as ulcerative colitis or Crohn disease. It is also used as a screening test to determine the possibility of bacterial colitis.
Detection of fecal lactoferrin allows for the differentiation of inflammatory and noninflammatory intestinal disorders in patients with diarrhea. Usually the test is used as a diagnostic aid to help identify patients who have active Inflammatory Bowel Disease (such as Crohn Disease or Ulcerative Colitis) and help to rule out patients with Active Irritable Bowel Syndrome, which is noninflammatory. Lactoferrin is also present in patients with bacterial enteritis such as Shigella, Salmonella, Campylobacter jejuni, and Clostridium difficile. Diarrhea caused by viruses and most parasites is not associated with elevated lactoferrin levels. Lactoferrin testing is often used as a screening test for patients who may have bacterial enteritis. If the stool is negative for lactoferrin, it is unlikely that a stool culture will be positive.
The lactoferrin analyte may be qualitatively detected by two distinct methods: (1) A latex agglutination procedure (the most commonly used) and (2) a microwell enzyme immunoassay procedure. The former method has been used primarily in the evaluation of patients with diagnoses of bacterial infectious gastroenteritis, while the latter method has been developed primarily as a diagnostic aid to distinguish between active inflammatory bowel disease and active noninflammatory irritable bowel syndrome.
Indications of Lactoferrin Positive Findings
Lactoferrin if found in patient who have conditions associated with an Inflammatory Immune Response of WBCs which are forms of Inflammatory Bowel Disease. These diseases are:
- Bacterial enteritis.
- Acute Crohn disease.
- Acute ulcerative colitis.
Breastfed infants will test positive for Lactoferrin because breast milk contains Lactoferrin. This test cannot be used to diagnose Inflammatory Bowel Disease for breastfed infants. Consuming any kind of milk that contains Lactoferrin wouldn’t interfere with the test results since the antigen used in the test only engages with human Lactoferrin.