IgA (Immunoglobulin A)

What is IgA (Immunoglobulin A)?

The main antibody in mucous membranes like the gut and airways; helps assess mucosal immunity and screen for IgA deficiency.

IgA is the main antibody found in mucosal secretions such as saliva, tears, and the linings of the gut and respiratory tract, where it helps form a first line of defense against pathogens. Total IgA is commonly measured as a foundation for interpreting other IgA-based antibody tests, such as celiac disease serology, since low overall IgA can cause those tests to appear falsely negative. Persistently low IgA is associated with certain immune deficiencies and recurrent infections, while elevated IgA can be seen with chronic liver disease or ongoing inflammatory conditions. This result is generally interpreted together with IgG, IgM, and clinical context rather than in isolation.

Lifestyle factors that influence this marker

• Aim for a balanced, nutrient-rich eating pattern that supports overall immune and gut health
• Stay physically active with regular moderate exercise
• Prioritize consistent, restorative sleep
• Practice stress-management techniques
• Avoid smoking
• Moderate alcohol intake

Tests often checked alongside this

• IgG (Immunoglobulin G) — often reviewed together as part of a full immunoglobulin panel
• IgM (Immunoglobulin M) — often reviewed together as part of a full immunoglobulin panel
• Deamidated Gliadin IgA — interpreted alongside total IgA when screening for celiac disease

How this can show up in how you look and feel

• May be associated with recurrent sinus or respiratory infections if persistently low
• May be associated with digestive symptoms
• May be associated with fatigue

What can affect this marker

• Age
• Sex
• Pregnancy
• Medications
• Infection
• Lab variability between testing methods

What to track over time

• Whether levels remain stable if monitoring a known deficiency or condition
• How this result correlates with infection frequency over time
• Whether it is checked before ordering other IgA-based antibody tests

What to ask your doctor

• Does my IgA level affect how other antibody tests, like celiac testing, should be interpreted?
• Should IgG and IgM also be checked as a full panel?
• Could this be related to my infection history?
• Is any follow-up testing recommended?

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