Immunoglobulin A (IgA): What Your Result Means

What is Immunoglobulin A (IgA)?

Immunoglobulin A is the immune system's mucosal defender, produced at the linings of the gut, lungs, and other surfaces. Its level is checked for two main reasons: to investigate frequent infections (looking for immune deficiency) and to validate celiac antibody testing, because IgA deficiency makes the standard celiac test falsely negative. IgA also rises with chronic inflammation and some liver diseases.

Typical reference interval: Normal serum IgA is commonly roughly 70-400 mg/dL (varies by age; children run lower). The lab's age-matched range governs. About 1 in 300-500 people have selective IgA deficiency.. Laboratories differ — the interval printed on YOUR report always governs.

If your Immunoglobulin A (IgA) is high

Common reasons Immunoglobulin A (IgA) runs above the reference interval:

• Chronic infection or inflammation — sustained immune stimulation raises IgA
• Liver disease — IgA is cleared by the liver — certain liver conditions let it accumulate
• Autoimmune and gut disease — conditions like celiac and inflammatory bowel disease can raise it
• Some cancers — plasma-cell and certain other tumors overproduce IgA
• Alcohol-related liver injury — a recognized cause of elevated IgA

If your Immunoglobulin A (IgA) is low

Common reasons Immunoglobulin A (IgA) runs below the reference interval:

• Selective IgA deficiency — the most common primary immune deficiency — often no symptoms at all, found incidentally
• Celiac-testing caveat — low IgA makes the standard tTG-IgA celiac test unreliable — total IgA must be checked alongside
• Medication effects — some antiseizure and immune-modulating drugs lower IgA
• Other immune deficiencies — low IgA can accompany broader antibody deficiency syndromes

Symptoms worth knowing

Selective IgA deficiency is usually silent — most people never know. When problems occur, they are usually infections of the gut, sinuses, or lungs, or autoimmune conditions. High IgA causes no direct symptoms; it reflects the underlying inflammatory process.

What usually happens next

1. A low IgA with frequent infections warrants an immunology review and broader antibody testing
2. If you are being tested for celiac, low IgA means the tTG-IgA result cannot be trusted — a clinician orders a different celiac test
3. High IgA is interpreted with liver and inflammatory markers, not alone

Frequently asked questions about Immunoglobulin A (IgA) results