What does the Secretory Immunoglobulin A test measure?

Why is Secretory Immunoglobulin A measured?

Low faecal sIgA may reflect mucosal immune deficiency, chronic stress, malnutrition, or dysbiosis, and is associated with increased susceptibility to enteric infection and food sensitivities. Elevated sIgA can indicate an active mucosal immune response to pathogens or chronic antigen exposure. Interpretation is exploratory; clinical utility is debated and thresholds are not standardised.

Reference ranges

Standard reference

Laboratory-specific; typically 0.5–2.0 mg/dL or similar.

Functional medicine optimal

Mid-range laboratory reference; low values (<0.5 mg/dL) may prompt investigation of immune function, gut barrier integrity, and chronic stress; very high values suggest active mucosal challenge.

Units

µg/mL, mg/dL, µg/g

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.