Secretory IgA in Feces – Role and Importance of Testing

What is Secretory IgA in Feces?

Immunoglobulin A (IgA) is an antibody that plays a significant role in the body’s immune response. In its secretory form, it is found in mucus and bodily secretions, including stool, and is the most important immunoglobulin present in mucosal secretions. This makes it crucial for protecting the body from pathogens. Secretory IgA can be considered a biomarker used to assess gut immunity and barrier function.

Why is Testing for Secretory IgA in Feces Important?

Secretory IgA serves as the first line of defense against pathogens and antigens (such as food residues, bacteria, parasites, yeasts, viruses, and allergens). Testing for secretory IgA in feces provides valuable information for evaluating the immune system’s overall function and its local activity in the gastrointestinal tract (which accounts for approximately 70-80% of the total immune system). This test is used to assess immunological activity in the gastrointestinal tract and monitor intestinal infections. Additionally, it helps track the effectiveness of treatment in patients with inflammatory bowel diseases (such as Crohn’s disease or ulcerative colitis). A decrease in secretory IgA levels may indicate a response to treatment or a worsening of the condition.

What is Required for the Secretory IgA Test?

Collecting a sample for this test is simple and non-invasive. The patient is given a container for stool collection, along with instructions. The sample should be collected in a sterile container and delivered to the laboratory. No special preparation is required from the patient.

Elevated and Decreased Levels of Secretory IgA in Feces

Elevated concentrations of secretory IgA can indicate a strong immune response to an antigen or pathogen, while decreased levels suggest reduced mucosal immunity.

Reference Values for Secretory IgA in Feces

The results of secretory IgA tests in feces can vary depending on the type of test used by the laboratory and the manufacturer’s recommended reference range. It is important that result interpretation considers the patient’s clinical picture. When monitoring the expected increase or decrease in secretory IgA levels, it is advisable to repeat the tests using the same method to ensure traceability of the results.
At BioDiagnostica this analysis is performed using the ELISA method, and the results are expressed in mg/L:

For efficient production of secretory IgA, the body needs to have sufficient amounts of vitamin C, zinc, glycine, phosphatidylcholine, glutathione, and other nutrients. Lifestyle and nutritional habits are crucial for overall immunity, including gastrointestinal health.