Skip to content
Blood Test Tracker

Immunoglobulin A (IgA)

An antibody that guards the linings of your gut, airways and mouth. It is also the control for celiac blood tests.

AI-verified against cited sources. Awaiting expert reviewAlso called IgALOINC 2458-8

Check your result

Sex (optional)

Type your result to see where it falls.

Nothing you type here leaves your browser.

What it is

IgA is an antibody found in your blood and, in larger amounts, in your saliva, tears, breast milk and the linings of your airways and gut, where it acts as a first line of defense. This test measures the IgA in your blood. It is also checked alongside celiac disease blood tests, because some of those tests rely on IgA antibodies.

Why it matters

Total IgA helps your care team understand your immune defenses and read gut-related antibody tests. Low IgA is fairly common, and many people with low IgA have no symptoms. If IgA is very low, celiac antibody tests that depend on IgA can look falsely negative, so your clinician may use IgG-based tests instead. A high IgA is often seen with liver conditions or long-running inflammation, and sometimes with a single-antibody (monoclonal) rise.

If it’s low

A low IgA means your blood holds less of this antibody than is usual for your age. Low IgA is the most common antibody difference, and most people who have it feel fine and learn about it by chance. Some have more sinus, lung or gut infections, allergies or autoimmune conditions. Many other things can cause this, and your clinician can put it in context.

Common causes

  • Selective IgA deficiency, which is common and often causes no symptoms
  • Very young age, since IgA is naturally low in babies and rises through childhood
  • Some medicines, such as certain anti-seizure drugs and steroids
  • Protein loss through the kidneys or the gut, or severe burns
  • Malnutrition or malabsorption
  • Common variable immunodeficiency (uncommon), usually with low IgG as well

What can help

  • If you're being checked for celiac disease, ask whether IgG-based celiac tests should be used because of low IgA
  • Ask whether IgG and IgM were normal, and whether you should recheck this later
  • Ask whether your care team and any blood bank should know about a very low IgA level before a transfusion

If it’s high

A high IgA most often reflects a broad rise from long-running inflammation, liver disease or infection. Less often it comes from one clone of plasma cells making a single antibody. Many other things can cause this, and your clinician can put it in context.

Common causes

  • Acute and long-lasting (chronic) infections
  • Pregnancy or hard exercise
  • Liver conditions, including hepatitis and cirrhosis
  • Autoimmune and connective tissue conditions
  • Alcohol use disorder
  • IgA nephropathy, a kidney condition in which IgA is often raised
  • Treatment with asparaginase, a cancer medicine (Mayo IgG page)
  • A monoclonal gammopathy, such as MGUS or multiple myeloma

What can help

  • Ask whether protein electrophoresis would help tell a broad rise from a single-antibody (monoclonal) rise
  • Ask whether your liver tests or kidney tests are worth a look

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

The usual range depends on sex and age. Choose women or men to see the one that applies.

Children and teens 12 ranges

See IgA by age and sex, with the U.S. survey numbers where they exist.

Selective IgA deficiency threshold (ESID/PAGID definition, as described in Yel 2010)

  • Under 7 mg/dL (the level used to define IgA deficiency when IgG and IgM are normal)below 7 mg/dL
  • 7 mg/dL or higher7 and above mg/dL

If this applies to you

IgA means a little more for some people. Open the one that fits you.

Celiac disease or IBD

ACG suggests measuring total IgA at the same time as the first tTG-IgA, if it hasn't been checked before. If IgA is low, ACG uses IgG-based celiac tests instead, such as DGP IgG or tTG IgG.

Blood tests for celiac disease and IBD

What can affect your result

  • Age: IgA is lowest in infants and rises through childhood (Mayo)
  • Sex: Labcorp prints different intervals for males and females, while Mayo and ARUP print one interval for all adults
  • Pregnancy, hard exercise and alcohol use disorder can raise IgA, and some medicines such as phenytoin and steroids can lower it (Mayo IgG page)
  • Method: nephelometry and turbidimetry assays from different manufacturers are not always comparable
  • Very cloudy (lipemic) samples can't be measured reliably. Mayo rejects grossly lipemic specimens, and ARUP lists grossly hemolyzed and lipemic specimens as unacceptable.
  • Results from different manufacturers' methods may not be comparable, so compare your results using the same lab and method when you can (Mayo).
  • Some medicines can lower IgA, including phenytoin (diphenylhydantoin), dextran, methylprednisolone and oral contraceptives (Mayo IgG page). Tell your clinician about everything you take, and don't stop a medicine without asking.

IgA changes over weeks to months.

When to talk to a clinician

Talk with your clinician about a high or low result, especially if you've had repeated sinus, lung or gut infections or ongoing diarrhea. An IgA under 7 mg/dL (0.07 g/L) is the level at which clinicians call IgA deficient when IgG and IgM are normal, so tell your care team if you have a result that low before any blood transfusion. Let them know sooner about bone pain, a fracture after a minor injury, numbness or tingling, or unusual tiredness.

Questions you could ask

  • Does my IgA fit with my history of infections or gut symptoms?
  • Is my IgA rise broad or from a single antibody, and would protein electrophoresis help?
  • Could a liver, kidney or inflammatory condition explain it?
  • Were my IgG and IgM normal, and does that change how we read a low IgA?
  • If I'm being tested for celiac disease, should we use IgG-based tests?

Questions people ask

Why does a celiac test ask for my total IgA?

Many celiac antibody tests measure IgA antibodies. If your total IgA is very low, those tests can read negative even when celiac disease is present, so clinicians check total IgA first and may use IgG-based celiac tests when it is low.

Is low IgA harmful?

Most people with low IgA are healthy and have no symptoms. Some get more respiratory or gut infections, allergies or autoimmune conditions, and a very low level matters for blood transfusions. Your clinician can tell you what it means for you.

Why does my lab's range differ from the one shown here?

Labs use different instruments and set ranges from different groups of healthy people. For adults, the lower limit runs from about 61 to 90 mg/dL and the upper limit from about 325 to 408 mg/dL across Mayo, ARUP, Labcorp and ABIM. Use the range printed on your own report first.

Show the science and sources

Units

  • 1 mg/dL = 1 mg/dL
  • 1 mg/dL = 0.01 g/L
  • 1 mg/dL = 10 mg/L

Open the IgA unit converter

Is a change real?

IgA naturally varies about 3.3% from test to test in the same healthy person. Between two results from the same lab, a change of roughly 10% or more is unlikely to be day-to-day noise or lab variation (95% reference change value). Source: The European Biological Variation Study (EuBIVAS): a summary report.

For clinicians and researchers

IgA is the most abundant antibody isotype made in the body; IgA1 is mostly monomeric in blood, while dimeric secretory IgA (mostly IgA2) dominates mucosal secretions (Yel 2010). About 15% of the immunoglobulin in the gamma zone on serum protein electrophoresis is IgA (Mayo). It is measured by nephelometry (Mayo) or immunoturbidimetry (ARUP). The usual definition of selective IgA deficiency (ESID/PAGID, as described by Yel 2010) is a decreased or absent serum IgA with normal IgG and IgM in a person older than 4 years, after other causes of low immunoglobulins are excluded. A serum IgA under 7 mg/dL (0.07 g/L) is the usual cut-off because it is the lowest detectable limit of most labs; a level above 7 mg/dL but 2 SD below the age mean is called partial IgA deficiency (Yel 2010). In US community studies the frequency is estimated at 1 in 223 to 1 in 1,000 (Yel 2010). In IgA deficiency, celiac screening should include IgG-based antibodies, because IgA-based tests can be falsely negative. Some IgA-deficient people make anti-IgA antibodies that can cause reactions to blood products containing trace IgA (Yel 2010). Mayo's immunoglobulin pages list diphenylhydantoin (phenytoin), dextran, methylprednisolone, toluene, xylol and oral contraceptives as agents that may lower IgA, and asparaginase, pregnancy, exercise and alcohol use disorder as factors that raise it (Mayo IgG page). Elevated IgA may be polyclonal (liver disease, connective tissue disease, infection) or monoclonal (multiple myeloma, amyloidosis, MGUS), and electrophoresis and immunofixation separate the two (Mayo).

LOINC 2458-8 (primary). Specimen: serum-or-plasma.

Sources

  1. Immunoglobulin A (IgA), Serum (test ID IGA), Mayo Clinic Laboratories
  2. Immunoglobulin G (IgG), Serum (test ID IGG), Mayo Clinic Laboratories
  3. Immunoglobulins (IgA, IgG, IgM), Quantitative (test 0050630), ARUP Laboratories
  4. Pediatric Testing Reference Ranges (includes adult intervals for Labcorp tests 001776, 001784, 001792 and 001834), Labcorp Diagnostics
  5. ABIM Laboratory Test Reference Ranges, January 2026, American Board of Internal Medicine (2026)
  6. Immunoglobulins Blood Test, MedlinePlus (National Library of Medicine) (2025)
  7. Selective IgA Deficiency, Journal of Clinical Immunology (2010)
  8. Comparison of Diagnostic Criteria for Common Variable Immunodeficiency Disorder, Frontiers in Immunology (2014)
  9. LOINC code lookup (NLM Clinical Tables), National Library of Medicine

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

Related markers