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Immunoglobulin A (IgA)

Published: July 27, 2026Updated: August 25, 2026

IgA is an antibody that plays a crucial role in the immune function of mucous membranes. It is often measured to assess the body's immune response and mucosal immunity.

Quick summary

IgA is a key antibody for mucosal immunity and immune response evaluation.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
mg/dL
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Roche IgA, Abbott IgA, Siemens IgA, Beckman IgA
interpretation: {"text":"Levels below 70 mg/dL may indicate an IgA deficiency, which can increase susceptibility to infections, particularly in the mucous membranes.","label":"Low IgA"}; {"text":"Levels above 400 mg/dL may suggest chronic infections, autoimmune disorders, or other inflammatory conditions.","label":"High IgA"}

Immunoglobulin A (IgA) is the most abundant antibody type found in the mucous membranes that line the respiratory and digestive tracts, as well as in saliva, tears, and breast milk. It serves as the first line of defense against pathogens at these entry points.

IgA levels are commonly tested to diagnose and monitor various immune-related conditions, such as infections, autoimmune disorders, and deficiencies in the immune system. Abnormal IgA levels can indicate an overactive or underactive immune response.

The reference range for IgA is typically between 70–400 mg/dL. Levels below this range may suggest an IgA deficiency, while higher levels could indicate chronic infections, autoimmune diseases, or other inflammatory conditions.

Frequently asked questions

What does a low IgA level mean?
A low IgA level may indicate an IgA deficiency, which can result in increased susceptibility to infections, especially those affecting the mucous membranes.
Can IgA levels change over time?
Yes, IgA levels can fluctuate based on the presence of infections, inflammatory conditions, or other immune-related factors.
  1. 1
    Immunoglobulin A (IgA)Source
  2. 2
    IgA DeficiencySource

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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy