As of January 30th, 2017 the test for Fecal Leukocytes will be discontinued and replaced with testing for Fecal Lactoferrin.
The microscopic examination of stained fecal preparations for leukocytes has been used for many years as a diagnostic tool for the detection of intestinal inflammation. In a patient with diarrhea, the presence of fecal leukocytes can be associated with inflammatory bowel disease, invasive bacterial enteritis, and amebiasis. However, this microscopic method is subjective, requires highly trained laboratory staff, and suffers from poor sensitivity and specimen stability.
Lactoferrin is a glycoprotein found within the granules of polymorphonuclear cells (PMNs) and can be used as a marker for acute inflammation of the intestinal mucosa. This marker remains stable within the specimen despite rapid leukocyte deterioration. Lactoferrin antigen can be rapidly and reliably detected using an Enzyme Immunoassay (EIA) method. Testing for lactoferrin has enhanced clinical sensitivity (~90%) over leukocyte microscopy (<50%). The significantly higher sensitivity leads to additional positive results, which are attributable to the detection of lactoferrin from deteriorated leukocytes that would not otherwise be detected by microscopic staining. Until now, lactoferrin testing has only been available as a send-out test to a reference lab.
Specimen: Unlike testing for fecal leukocytes which required preserved stool due to specimen stability issues, fresh stool is submitted for lactoferrin testing and is stable for up to 14 days post-collection.
Clinical indication: Fecal lactoferrin is used as an adjunctive test to monitor for intestinal inflammation. Positive lactoferrin results alone are not diagnostic for infectious or non-infectious processes and should be used in conjunction with imaging, endoscopy, histology, microbiology testing, etc.
Fecal leukocytes: http://spectrumhealth.testcatalog.org/show/8895
Fecal lactoferrin: https://spectrumhealth.testcatalog.org/show/LAB3647-1