From the Research
Total intestinal secretory IgA (sIgA) measured in stool samples is a valuable marker of mucosal immune function in the gastrointestinal tract, with normal values typically ranging from 510-2040 μg/g, though reference ranges may vary between laboratories. This test measures the levels of secretory immunoglobulin A, which is the predominant antibody class in mucosal secretions and serves as the first line of immunological defense against pathogens at mucosal surfaces. Low levels of stool sIgA may indicate compromised mucosal immunity, which can be associated with food sensitivities, inflammatory bowel conditions, or recurrent infections. Elevated levels often suggest ongoing immune activation in response to pathogens or inflammation.
The test requires a fresh stool sample collected in appropriate containers provided by the laboratory. No specific preparation is typically needed before collection, though patients should follow any instructions provided by their healthcare provider. Results should be interpreted by a healthcare professional in the context of clinical symptoms and other diagnostic findings, as both low and high values can be meaningful depending on the clinical situation. This test is particularly useful in evaluating intestinal barrier function, monitoring inflammatory conditions, and assessing immune status in the gut. According to a recent study 1, there is a link between small intestinal bacterial overgrowth (SIBO) and celiac disease (CeD), which may be related to alterations in sIgA levels.
Some key points to consider when interpreting sIgA results include:
- Low sIgA levels may indicate compromised mucosal immunity
- Elevated sIgA levels may suggest ongoing immune activation
- sIgA levels can be influenced by various factors, including SIBO and CeD
- Results should be interpreted in the context of clinical symptoms and other diagnostic findings As noted in a study published in 2023 2, SIBO is a condition defined by the excess bacteria or changes in bacterial composition of the small intestine, which can lead to various gastrointestinal symptoms. Another study from 2022 1 found that SIBO prevalence in CeD patients was significantly increased, with a pooled prevalence of 18.3%.
In terms of clinical application, measuring total intestinal sIgA in stool samples can be a useful tool in evaluating patients with suspected SIBO or CeD, particularly those who are non-responsive to a gluten-free diet. However, it is essential to consider the results in the context of clinical symptoms and other diagnostic findings, as both low and high values can be meaningful depending on the clinical situation. As noted in a study from 2017 3, the pooled mean prevalence of SIBO in CD was 20%, and SIBO could be more common in CD when symptoms do not improve after a gluten-free diet.