A positive result on a lactoferrin stool test means that inflammation is actively occurring within your gastrointestinal (GI) tract. Lactoferrin is a protein released by neutrophils, a type of white blood cell rapidly deployed to the intestinal lining when the body detects a threat or injury. The test is a non-invasive way to check for this protein in a stool sample. Finding lactoferrin confirms an inflammatory process is underway, distinguishing between inflammatory and non-inflammatory causes of symptoms like diarrhea and abdominal discomfort. The test provides a quantifiable measure of the body’s immune response in the gut.
Understanding Lactoferrin as an Inflammatory Marker
Lactoferrin is a glycoprotein that serves an important function in the body’s innate immune system. It is stored within the granules of neutrophils, the most abundant type of white blood cell, and is released when these cells become activated in response to inflammation or infection. When the lining of the intestines is damaged or irritated, neutrophils migrate from the bloodstream into the gut tissue to mount a defense.
As these immune cells congregate and break down in the intestinal wall, they shed their contents, including lactoferrin, directly into the bowel. This protein then passes out of the body, where its presence in the stool can be measured. A positive result, therefore, acts as a reliable surrogate marker for the presence of activated white blood cells in the gut.
The test is quantitative, meaning it measures the specific amount of lactoferrin in micrograms per gram of stool. Higher concentrations of the protein generally correlate with a greater number of neutrophils present and a more severe degree of intestinal inflammation. A normal or low lactoferrin level suggests that the symptoms are likely due to a non-inflammatory issue, such as Irritable Bowel Syndrome (IBS).
This measurement helps confirm that the patient’s symptoms are rooted in actual tissue inflammation rather than a functional disorder. The test is considered a non-specific inflammatory marker because it confirms the presence of inflammation but cannot identify the precise cause or location within the GI tract. Despite this non-specificity, the quantitative nature of the test provides a valuable baseline for monitoring the activity and severity of the inflammation over time.
Conditions Associated with Elevated Stool Lactoferrin
An elevated lactoferrin result points directly toward a condition that causes neutrophil infiltration and inflammation in the intestinal lining. The most frequent reason this test is ordered is to help differentiate between chronic inflammatory diseases and acute infectious causes. The presence of lactoferrin suggests an organic disease is present, which requires further investigation.
Inflammatory Bowel Disease (IBD), encompassing Crohn’s disease and Ulcerative Colitis, is a primary cause of chronically elevated lactoferrin. In patients with IBD, the immune system attacks the gut lining, causing persistent inflammation and high levels of lactoferrin to be released. Elevated lactoferrin levels are highly specific for IBD, helping physicians distinguish these conditions from Irritable Bowel Syndrome (IBS).
Acute infectious colitis, caused by certain types of bacteria, is another common reason for a positive result. Pathogens such as Clostridium difficile (C. diff), Salmonella, and Campylobacter trigger a strong immune response, leading to a temporary but significant increase in stool lactoferrin. In these cases, the elevated level is a sign that the body is actively fighting an infection.
Less common causes of intestinal inflammation can also lead to a positive lactoferrin test. These include enteropathy caused by the prolonged use of non-steroidal anti-inflammatory drugs (NSAIDs) or severe food protein-induced enterocolitis syndrome. All of these conditions share the common mechanism of causing damage to the intestinal mucosa, which recruits neutrophils.
Interpreting Results and Subsequent Diagnostic Steps
A positive lactoferrin result serves as an important screening tool, but it is not a final diagnosis on its own. The test confirms the existence and relative severity of intestinal inflammation, but it cannot specify whether the inflammation is due to IBD, an infection, or another cause. Further testing is always necessary to pinpoint the exact underlying condition.
For patients with symptoms suggestive of an acute infection, the next step involves specific stool cultures or molecular tests to identify bacterial pathogens like C. difficile or Salmonella. If infectious causes are ruled out, a positive lactoferrin strongly suggests a chronic inflammatory process, most notably IBD. The level of the lactoferrin can also be used to monitor disease activity in patients already diagnosed with IBD.
To definitively diagnose IBD, the gold standard procedure is typically an endoscopy or colonoscopy with a biopsy. These invasive tests allow the physician to visually inspect the internal lining of the GI tract and collect tissue samples for microscopic examination. The lactoferrin test helps determine which patients with non-specific GI symptoms require these more intensive diagnostic procedures.
Results should be discussed with a gastroenterologist, as they interpret the numbers in the context of your medical history and other symptoms. Certain factors can affect the results, such as the consumption of breast milk in infants or the use of specific medications. The test is a guide that directs the next steps in the diagnostic investigation.