An IgA blood test measures how much immunoglobulin A is circulating in your bloodstream, and it is one of the more commonly misread numbers on an immune panel. IgA is an antibody your body makes in large quantities to guard the moist surfaces that meet the outside world: your airways, your gut, your eyes, and your mouth. Because those surfaces are constantly exposed, the level shifts with age, with ongoing infections, with liver health, and occasionally with an inherited quirk of the immune system that many people never notice. In this article you will learn what the test measures, how to read the number against your laboratory’s reference range, what pushes IgA higher or lower, why a low result matters when celiac disease is being ruled out, and what recent research says about the kidney condition that carries IgA in its name.
What an IgA blood test measures
Immunoglobulin A is one of five antibody classes your immune system makes, alongside IgG, IgM, IgD, and IgE. A laboratory measures serum IgA by mixing your sample with reagents that bind to IgA and reading how cloudy the mixture becomes, then converting that into a concentration reported in milligrams per deciliter.
The test is almost always ordered as part of a panel rather than alone. Most laboratories report IgA alongside two companion antibodies, so it helps to know how clinicians read the IgG antibody that dominates long-term immunity and how they interpret the IgM antibody that appears early in a new infection. Read together, the three numbers sketch a rough map of how your antibody-producing machinery is working.
One limitation deserves stating up front. A serum IgA result tells you the quantity of IgA in blood, not whether that IgA is working properly or what it is targeting. Those questions require different tests entirely.
How your body makes and uses IgA
Plasma cells, the mature form of a white blood cell called a B lymphocyte, manufacture IgA, mostly in the tissue lining your gut, airways, and glands rather than in the bloodstream. Your body makes more IgA each day than all other antibody classes combined, and most of it never enters your blood at all.
Serum IgA and secretory IgA are not the same thing
IgA exists in two practical forms. Serum IgA travels as a single unit in the bloodstream and is what a standard blood test reports. Secretory IgA travels as a linked pair wrapped in a protective component that helps it survive stomach acid and tears; it is what you find in saliva, breast milk, and intestinal mucus, and it does most of the day-to-day defensive work.
Two subtypes, IgA1 and IgA2, differ slightly in structure. Serum IgA is mostly IgA1, while secretory IgA in the gut is richer in IgA2, a form better able to resist the enzymes bacteria use to chop antibodies apart. That detail matters, because the kidney condition known as IgA nephropathy involves an altered version of IgA1 specifically.
What IgA actually does
IgA works largely by a strategy called immune exclusion. Rather than triggering inflammation, it binds viruses, bacteria, and food proteins and traps them in mucus so they are swept out before they can attach to a cell. That quiet approach is why healthy mucous membranes tolerate an enormous bacterial population without constant irritation, and it helps keep gut bacteria in balance.
What to expect before, during, and after the test
An IgA test uses an ordinary blood draw from a vein in your arm. No fasting or special preparation is required, and the draw takes a minute or two.
Tell whoever orders the test about any medication you take. Corticosteroids, some anti-seizure medications, and immunosuppressants can all shift immunoglobulin levels, as can a recent vaccination, an active infection, or a transfusion. Results usually return within a few days, often alongside the total protein value that sums all circulating proteins, which gives context to any antibody abnormality.
How to read your IgA blood test results
Your result appears in milligrams per deciliter next to a reference range printed by the laboratory that ran the sample, and that range is the crucial part. Laboratories use different instruments and different local populations to define what counts as typical, so a value read as normal at one facility can be flagged at another.
Age matters more for IgA than for most markers. Newborns have almost no serum IgA because, unlike IgG, it does not cross the placenta; levels climb through childhood and only reach adult values in the late teens or early twenties. Treat the table below as orientation rather than as your personal cutoff.
| Age group | Commonly reported serum IgA range (mg/dL) | What to keep in mind |
|---|---|---|
| Newborn | Very low, often near zero | IgA does not cross the placenta, so a newborn starts with essentially none of its own |
| Infant, 1 to 12 months | Roughly 1 to 80 | Production is just beginning; a low value at this age is expected, not alarming |
| Child, 1 to 12 years | Roughly 20 to 200 | The range widens steadily; interpretation should use a pediatric reference table |
| Teenager, 13 to 17 years | Roughly 40 to 350 | Values are approaching but not yet at adult levels |
| Adult | Roughly 60 to 400 | Levels tend to drift slightly upward with age across adulthood |
Why a single number rarely settles anything
Reference ranges are built by measuring healthy volunteers and defining the range as the middle portion of their results, so by design a small share of perfectly healthy people fall outside it. A result just past the printed edge is common and often meaningless on its own. Clinicians look instead for a value far outside the range, one drifting consistently across repeated tests, or one that fits a story your symptoms already tell. For a broader walkthrough, this guide to reading reference ranges and result flags covers the mechanics.
What high and low IgA levels can mean
Neither a high nor a low IgA result is a diagnosis. Each points toward a set of possibilities your clinician narrows down with history, symptoms, and further testing. The table below groups the reasons most often considered.
| Result direction | Reasons a clinician commonly considers | Typical next step |
|---|---|---|
| Mildly high | An ongoing or recent infection of the airways or digestive tract, or long-term inflammation | Repeat the test after the episode resolves and check inflammation markers |
| Persistently high | Chronic liver disease, including alcohol-related liver injury and cirrhosis | Liver enzyme panel, imaging, and a review of alcohol and medication history |
| Persistently high | Autoimmune conditions such as rheumatoid arthritis or inflammatory bowel disease | Targeted autoantibody testing guided by symptoms |
| Very high and isolated | A single clone of plasma cells producing one antibody in excess | Protein electrophoresis and, if indicated, referral to a blood specialist |
| Low | Selective IgA deficiency, the most common inherited immune difference | Confirm with a repeat test and check IgG and IgM to rule out broader deficiency |
| Low | Protein loss through the kidneys or gut, or a medication suppressing the immune system | Urine protein testing, nutritional review, and a medication check |
Understanding a high IgA result
Raised IgA usually reflects an immune system working hard rather than malfunctioning. Because IgA is produced at mucous surfaces, prolonged irritation anywhere along the airway or digestive tract lifts the number, and chronic liver disease is another frequent driver because a damaged liver clears IgA less efficiently. Clinicians often read a raised IgA alongside the C-reactive protein value that rises during active inflammation, since the pair distinguishes a temporary response from a persistent process.
When IgA is very high and the other antibody classes are low, laboratories may separate blood proteins by electrophoresis to see whether one narrow band dominates. That pattern shows up in the gamma globulin fraction that contains circulating antibodies and is one route by which a plasma cell disorder such as multiple myeloma and its characteristic protein spike comes to light. This is uncommon; a modestly elevated IgA is far more likely to reflect infection or inflammation.
Understanding a low IgA result
Selective IgA deficiency means a very low or undetectable serum IgA while IgG and IgM remain normal. It is the most common inherited immune difference in people of European descent, and many who have it live entirely ordinary lives, discovering it only when a blood test is run for another reason. Others notice more frequent sinus and respiratory infections, digestive complaints, or allergies.
Two practical consequences are worth knowing. People with IgA deficiency have a somewhat higher chance of developing autoimmune conditions over time, and in rare cases can react to blood products containing IgA, which is why the finding belongs in your medical record and should be mentioned before any transfusion or surgery.
Why IgA matters when celiac disease is being ruled out
The most frequent reason a total IgA test is ordered has nothing to do with immune deficiency. It is a safety check on celiac disease screening. The standard first-line blood test for celiac disease measures an IgA antibody directed against tissue transglutaminase, usually shortened to tTG-IgA, and that test only works if you produce IgA in the first place.
If you have low or absent IgA, a tTG-IgA result can come back negative even when celiac disease is present, simply because there is no IgA to detect. Measuring total IgA at the same time catches that trap, and when total IgA is low the clinician switches to a test based on IgG antibodies. Anyone investigating celiac disease and its immune reaction to gluten should also know that testing is only reliable while you are still eating gluten regularly, since removing it beforehand can normalize the result.
IgA nephropathy and when the kidneys are involved
IgA nephropathy, also called Berger’s disease, is an autoimmune kidney condition in which clumps of IgA lodge in the glomeruli, the tiny filtering units of the kidney, and provoke inflammation. According to the National Institute of Diabetes and Digestive and Kidney Diseases it is more frequent in people aged roughly ten to forty, in men, and in those of East Asian or white European ancestry.
One point of confusion is worth clearing up. A high serum IgA on a routine panel does not diagnose IgA nephropathy, and many people with the condition have entirely normal total IgA. What matters in the kidney is a structurally altered form of IgA1 that clumps with other antibodies, not the overall quantity circulating, so diagnosis relies on urine findings, kidney function tests, and ultimately a biopsy.
The early signs appear in urine rather than blood: visible or microscopic blood, and protein leaking through the filter. Clinicians therefore look at the urine albumin level that signals filter leakage alongside the creatinine value used to estimate kidney filtration. Because it can progress silently over years, it is one recognized path toward chronic kidney disease and its long-term monitoring needs.
When to talk to your doctor about an IgA result
Most IgA results need no urgent action, but a few situations deserve a conversation rather than a wait-and-see approach. Use the list below as a prompt for your next appointment.
- Your IgA is low or undetectable and you are being tested for celiac disease, since the standard antibody test may need to be swapped for an alternative version.
- Your IgA is low and you have a history of repeated sinus, ear, or chest infections, or persistent digestive symptoms.
- Your IgA is high and you have symptoms suggesting liver strain, such as ongoing fatigue, abdominal discomfort, or yellowing of the skin or eyes.
- Your IgA is markedly high while IgG and IgM are low, which is a pattern worth investigating rather than repeating casually.
- You notice pink, red, or cola-colored urine, foamy urine, or new swelling in your legs and ankles, which point to the kidney rather than to the antibody level itself.
- Your IgA has moved substantially between two tests at the same laboratory without an obvious explanation such as a recent infection.
Bring your full report rather than a single number. Antibody results are read as a set, and a clinician will want to see IgG and IgM, any protein and kidney values, and how the current result compares with earlier ones.
Latest scientific advances
Research over the past three years has moved in two directions that matter for anyone holding a lab report: clarifying who should be screened for celiac disease, and rethinking what IgA in the kidney actually represents. Every study mentioned below appears in the Sources list.
Clearer guidance on who should be screened for celiac disease
A 2024 review in the journal Gastroenterology examined the evidence linking celiac disease to more than twenty other conditions and set out which groups warrant proactive antibody screening. Both IgA deficiency and IgA nephropathy appear on that list, alongside type 1 diabetes, thyroid autoimmunity, and close relatives of people with celiac disease. What this means for you is that if your report shows low IgA, a celiac screen is reasonable to ask about even without classic digestive symptoms. This was a review of existing studies rather than a new trial, so it reflects expert consensus rather than fresh evidence.
Blood markers that may one day reduce the need for a kidney biopsy
Two 2025 reviews, one in Seminars in Nephrology and one in Clinical Immunology, surveyed the biomarkers being tested for IgA nephropathy. Both reach the same conclusion: a kidney biopsy, meaning a small tissue sample examined under a microscope, remains the definitive test, while the most promising blood candidate is an altered form of IgA1 known as galactose-deficient IgA1, along with markers of complement activation, complement being a set of blood proteins that amplify immune attacks. What this means for you is that these are research tools today, not something to request at a routine visit, and a standard total IgA result still cannot confirm or exclude the condition.
A better picture of how IgA damages the kidney
A 2024 review in Frontiers in Immunology described IgA nephropathy as a sequence of steps rather than a single event: an altered form of IgA1 appears in the blood, other antibodies bind to it, the clumps settle in the kidney filters, and inflammation follows. What this means for you is a useful reframing. The problem is the shape and behavior of the IgA, not the amount, which is why a normal total IgA reading does not rule the condition out. The review also stresses that supportive care, particularly blood pressure control and reducing protein loss in urine, remains the foundation of treatment.
The first targeted treatment approved for the condition
A 2024 review in Drug Design, Development and Therapy described a formulation of the steroid budesonide engineered to release in the last part of the small intestine, where much of the problematic IgA is produced. It became the first medicine approved by the Food and Drug Administration, and by its European counterpart, specifically for primary IgA nephropathy in people at risk of rapid progression. What this means for you is that a condition once managed only with general supportive measures now has a treatment aimed at its origin. It is prescribed for a confirmed, biopsy-proven diagnosis, not for a high IgA number on a routine panel.
Glossary
| Term | Definition |
|---|---|
| Immunoglobulin A (IgA) | An antibody class that defends mucous surfaces such as the airways and digestive tract. It is measured in blood as serum IgA. |
| Secretory IgA | The paired, protected form of IgA found in saliva, tears, breast milk, and intestinal mucus. It is not what a standard blood test measures. |
| Plasma cell | A mature white blood cell that manufactures antibodies. Most IgA-producing plasma cells sit in tissue lining the gut and airways. |
| Reference range | The span of values a laboratory considers typical, based on its own instruments and population. Ranges differ between laboratories. |
| Selective IgA deficiency | Very low or absent serum IgA with normal IgG and IgM. It is the most common inherited immune difference and often causes no symptoms. |
| tTG-IgA | Short for tissue transglutaminase IgA, the first-line blood test for celiac disease. It relies on your body producing IgA normally. |
| Glomerulus | One of the microscopic filtering units in the kidney. IgA nephropathy involves antibody deposits collecting in these structures. |
| Protein electrophoresis | A laboratory technique that separates blood proteins into bands, used to check whether one antibody is being overproduced. |
| Immune exclusion | The way IgA works: trapping germs and proteins in mucus so they are cleared away without triggering inflammation. |
Frequently asked questions
What is a normal IgA level for an adult?
Most United States laboratories report an adult serum IgA range of roughly 60 to 400 mg/dL, but the exact numbers on your report are the ones that count. Laboratories set their own ranges based on their instruments and the population they serve, so a value considered normal at one facility can be flagged at another. Age also matters more for IgA than for many markers, since levels rise gradually through childhood and only reach adult values in the late teens or early twenties. Always compare your number to the range printed beside it rather than to a figure found online.
Does a high IgA level mean cancer?
In the large majority of cases, no. A raised IgA most often reflects an ongoing infection, chronic inflammation, or liver disease, all of which are far more common explanations. A blood cancer involving plasma cells can raise IgA, but that pattern usually looks distinctive: a very high level of one antibody class combined with low levels of the others, often alongside anemia, bone pain, or kidney changes. When that pattern appears, clinicians confirm it with protein electrophoresis rather than acting on the IgA number alone.
What causes low IgA levels?
The most common cause is selective IgA deficiency, an inherited difference in which the body makes little or no IgA while producing normal IgG and IgM. Other causes include medications that suppress the immune system, protein losses through the kidneys or intestines, and certain infections. In young children, a low result is often simply age-appropriate, since IgA production ramps up slowly and does not reach adult levels for years. Confirming a low result usually means repeating the test and measuring the other antibody classes.
Do I need to fast before an IgA blood test?
No fasting is required for an IgA test, and you can eat and drink normally beforehand. If IgA is being drawn as part of a wider panel that includes glucose or a lipid profile, the fasting instruction would come from those tests rather than from the IgA measurement. What is worth mentioning to whoever orders the test is your current medication list, any recent vaccination, and any infection you are currently fighting, since all three can shift the result.
Can a temporary infection change my IgA result?
Yes. Because IgA is produced in response to activity at mucous surfaces, a chest infection, sinus infection, or bout of gastroenteritis can raise the level for a period afterward. This is a normal response, not a sign of disease. For that reason clinicians often repeat a mildly elevated IgA once the episode has fully resolved, typically several weeks later, before treating the finding as meaningful.
If my IgA is low, do I need to tell anyone before surgery?
It is worth mentioning. A small number of people with very low or absent IgA can react to blood products that contain IgA, so surgical and transfusion teams like to know in advance. Carrying the information in your medical record, and repeating it before any procedure involving a possible transfusion, is a simple precaution. For most people with low IgA, no other restriction on daily life applies.
Sources
- MedlinePlus, National Library of Medicine — Immunoglobulins Blood Test — MedlinePlus Medical Test, reviewed 2025 — medlineplus.gov
- Cleveland Clinic — Immunoglobulin A (IgA): Function, Tests and Disorders — Cleveland Clinic Health Library, 2024 — my.clevelandclinic.org
- National Institute of Diabetes and Digestive and Kidney Diseases — IgA Nephropathy — NIDDK Health Information, 2025 — niddk.nih.gov
- Mayo Clinic Staff — Celiac Disease: Diagnosis and Treatment — Mayo Clinic Diseases and Conditions, 2023 — mayoclinic.org
- Zingone F, Bai JC, Cellier C, Ludvigsson JF — Celiac Disease-Related Conditions: Who to Test? — Gastroenterology, 2024 — doi.org/10.1053/j.gastro.2024.02.044
- Kamal F, Kim J, Lafayette R — Current Biomarkers of IgA Nephropathy — Seminars in Nephrology, 2025 — doi.org/10.1016/j.semnephrol.2025.151572
- Xu Z, Zhan H, Zhang J, et al. — New Biomarkers in IgA Nephropathy — Clinical Immunology, 2025 — doi.org/10.1016/j.clim.2025.110468
- Filippone EJ, Gulati R, Farber JL — Contemporary Review of IgA Nephropathy — Frontiers in Immunology, 2024 — doi.org/10.3389/fimmu.2024.1436923
- Barratt J, Kristensen J, Pedersen C, Jerling M — Insights on Nefecon, a Targeted-Release Formulation of Budesonide and Its Selective Immunomodulatory Effects in Patients with IgA Nephropathy — Drug Design, Development and Therapy, 2024 — doi.org/10.2147/DDDT.S383138
Further reading
- See how the most abundant blood protein is measured and interpreted in our albumin blood test results guide.
- Check the white blood cells that mature into antibody-producing plasma cells by reading our lymphocyte count interpretation guide.
- Track general inflammation alongside a raised IgA result with our erythrocyte sedimentation rate results guide.
- Explore the symptom picture that often prompts celiac testing in our gluten intolerance symptoms and causes guide.
- Understand how kidney filtration is monitored over time by reading our chronic kidney disease monitoring guide.
Understand your lab results with BloodSense
An IgA value only becomes useful when you can see it next to the rest of your report. The same number means something different depending on your age, on whether IgG and IgM are normal, on what your liver enzymes and kidney markers show, and on how the result compares with your own previous tests. BloodSense translates a full lab report into plain language, showing where each marker sits relative to its reference range and helping you follow patterns across visits instead of reacting to one flagged line. It is built to help you understand your results and prepare better questions for your clinician, not to diagnose or replace medical care.
