IgA is the main antibody found in mucous membranes (respiratory tract, gastrointestinal tract, saliva, tears).

It plays a critical role in first‑line defense against infections at mucosal surfaces.

Clinical uses include:

Diagnosing IgA deficiency, which predisposes to recurrent respiratory and gastrointestinal infections.

Supporting evaluation of celiac disease (IgA deficiency can affect serological testing).

Assessing immune system disorders and autoimmune conditions.

Monitoring chronic infections and certain liver diseases.

Often performed alongside IgG and IgM for a complete immunoglobulin profile.

Analyte: Serum IgA concentration (mg/dL).

Normal Range (varies by age and lab):

Adults: ~70–400 mg/dL

Abnormal Findings:

Low IgA: Suggests selective IgA deficiency, celiac disease, recurrent infections, or immunodeficiency.

High IgA: May indicate chronic infections, autoimmune diseases (e.g., rheumatoid arthritis, lupus), or liver disease.

Clinical Use:

Provides a marker of mucosal immunity and immune system health.

Helps guide diagnosis and management of immunodeficiency or autoimmune conditions.

Supports evaluation of chronic inflammatory and infectious diseases.