Immunoglobulin A (IgA), Qn, Serum High or Low: Results & Normal Range

Immunoglobulin A, Qn, Serum measures the total concentration of IgA antibody in your blood. "Qn" means quantitative — a numerical value rather than a positive/negative result. IgA is the second most abundant antibody in serum and the primary antibody protecting mucosal surfaces in the gut, lungs, and airways.

This test is not the same as celiac-specific IgA tests (such as tissue transglutaminase IgA or deamidated gliadin IgA). Those tests detect specific antibodies. This test measures total IgA concentration — an entirely different measurement.

Immunoglobulin A, Qn, Serum — quick answer

• What it measures: Total IgA antibody concentration in serum
• Normal range: 70–400 mg/dL in adults (varies by age and lab)
• Units: mg/dL (milligrams per deciliter) or g/L
• High result: Associated with chronic infection, liver disease, autoimmune conditions, IgA nephropathy, alcohol use disorder, or rarely IgA plasma cell disorders
• Low result: Most commonly selective IgA deficiency — the most common primary immunodeficiency
• Also called: IgA Qn Serum, IgA Total, Total IgA, Immunoglobulin A Quantitative, IgA (RDL), IgA Ser Qn, iga total.lc
• Cancer risk: Mildly elevated IgA does not usually indicate cancer — very high levels (typically >1,000 mg/dL) with other abnormal findings may require further testing
• WarningHigh: A portal flag indicating the result exceeded the reference range — not an emergency; requires clinical interpretation

"WarningHigh Immunoglobulin A, Qn, Serum" is a lab portal flag indicating the result exceeded the laboratory's reference range. It is not a medical emergency — it means the result should be interpreted in clinical context by your doctor.

Immunoglobulin A normal range by age

IgA levels rise from birth through adolescence and stabilize in adulthood.

Reference ranges vary by laboratory and assay method. Always use your lab's printed reference range.

Unit conversion: To convert mg/dL to g/L, divide by 100. For example, 200 mg/dL = 2.0 g/L.

What does high Immunoglobulin A, Qn, Serum mean?

A high IgA result means total IgA is above the laboratory reference range. Elevated IgA is a nonspecific finding — many different conditions can raise it, and a mildly elevated result alone does not indicate a specific diagnosis.

Common causes of high Immunoglobulin A, Qn, Serum:

• Chronic infection — respiratory or gastrointestinal
• Liver disease — especially alcohol-related cirrhosis
• Autoimmune conditions — rheumatoid arthritis, SLE, celiac disease
• Kidney disease — IgA nephropathy (Berger's disease)
• Alcohol use disorder
• Plasma cell disorders — IgA multiple myeloma, MGUS (rare)

When to follow up urgently: IgA >1,000 mg/dL, or elevated result alongside anemia, kidney dysfunction, bone pain, or an abnormal protein band on electrophoresis.

Does high IgA mean cancer? A mildly or moderately elevated IgA does not indicate cancer. The vast majority of elevated IgA results have benign causes — infection, liver disease, autoimmune conditions, or alcohol use.

However, markedly elevated IgA — particularly when accompanied by a sharp single peak on protein electrophoresis (M-spike), bone pain, anemia, kidney dysfunction, or hypercalcemia — may indicate a plasma cell disorder requiring further investigation:

• IgA multiple myeloma — accounts for approximately 20–25% of multiple myeloma cases; associated with very high monoclonal IgA
• Monoclonal gammopathy of undetermined significance (MGUS) — a precursor condition; often discovered incidentally
• IgA-type Waldenström macroglobulinemia or lymphoma — rare

If your IgA is elevated and your doctor is concerned about a plasma cell disorder, they may order serum protein electrophoresis (SPEP), immunofixation, free light chains, or a bone marrow evaluation.

Specific value context:

What does low Immunoglobulin A, Qn, Serum mean?

A low IgA result means total IgA is below the laboratory reference range. The most important cause to consider is selective IgA deficiency.

Selective IgA deficiency is the most common primary immunodeficiency, affecting approximately 1 in 300–500 people. It is defined as a serum IgA below 7 mg/dL with normal IgG and IgM. Many people with selective IgA deficiency are entirely asymptomatic and never know they have it.

Clinical implications of low IgA:

• Recurrent infections — particularly sinopulmonary and gastrointestinal
• Increased susceptibility to certain autoimmune conditions (celiac disease, SLE, rheumatoid arthritis)
• False-negative celiac screening tests — tTG IgA and DGP IgA tests require normal total IgA to be valid; if total IgA is very low, celiac testing requires IgG-based tests instead
• Risk of severe transfusion reactions in IgA-deficient individuals who have developed anti-IgA antibodies

Other causes of low IgA:

• Medications — some anticonvulsants, immunosuppressants, antimalarials
• Protein-losing conditions — nephrotic syndrome, protein-losing enteropathy
• Bone marrow disorders
• Acquired immunodeficiency conditions

Important note for celiac testing: The lab comment "Total serum IgA is elevated — consider mucosal inflammatory conditions or underlying gammopathy" appears on some celiac reflex panels when total IgA is outside the expected range. This is a reflexive lab comment, not a diagnosis.

Immunoglobulin A, Qn, Serum

Every lab result you’ve ever had, charted and explained.

Healthmatters is a tracker for your lab results. Upload a report from any lab, any country — every marker charted and explained.

Start with my report →

Beyond Immunoglobulin A, Qn, Serum — 10,000+ markers explained

One Immunoglobulin A, Qn, Serum result tells you where you are. Your history tells you where you’re heading. Upload your past lab reports and see this marker — and every marker on them —every marker charted against your own lab’s ranges.

Start with this report →

Frequently Asked Questions