Immunoglobulin A (IgA) - Serum
Immunoglobulin A (IgA) is a key antibody that defends your digestive system and respiratory tract from invading pathogens. This essential blood test measures the levels of IgA circulating in your serum, helping doctors evaluate how well your immune system is protecting these critical areas. High or low IgA levels can signal underlying immune system issues, frequently seen with problems like chronic diarrhea, recurrent sinus infections, asthma, allergies, or certain autoimmune disorders such as lupus and celiac disease. Testing your IgA levels provides important information used to diagnose and monitor conditions associated with abnormal immune responses. Understanding these levels is a vital step toward managing your overall health.
People typing “IgA antibodies” into search are usually hunting two different things: disease-specific IgA (like tissue transglutaminase IgA in celiac workup) versus total serum IgA as its own quantity. This entry is the second: how much IgA your plasma is carrying right now. That number matters because total IgA deficiency can silence IgA-based celiac tests and leave you with a false-negative while symptoms rage. It also frames chronic gut, airway, and autoimmune stories where immunoglobulin production is part of the plot. One draw does not decode every antibody name on a panel, but it answers whether your IgA factory is online.
Self-Pay Price Comparison
| Provider | Price | vs. Highest | Order |
|---|---|---|---|
Quest QuestHealth self-pay | Not Available | N/A | Check Provider Site · Quest |
LabCorp Labcorp OnDemand | Not Available | N/A | Check Provider Site · LabCorp |
GoodLabs Discount lab network | $15.00Best value | Best price | Order · GoodLabs |
What This Test Measures
The lab reports one serum concentration for immunoglobulin A; everything else on your requisition is interpreted against that backbone.
Quantifies circulating IgA, the antibody class that dominates mucosal surfaces and still appears measurably in serum. High levels point toward chronic immune activation or certain proliferative states; very low levels flag selective deficiency that breaks IgA-based celiac screens and raises mucosal infection risk.
How to Read Your Results
Serum IgA is one concentration line; here is how clinicians separate deficiency, chronic stimulation, and noisy border results.
| Marker | Normal Range | If Flagged | What It Might Mean |
|---|---|---|---|
| Serum IgA (below reference) | Laboratories set their own cutoffs; deficiency definitions often cite total serum IgA under roughly 7 mg/dL for selective deficiency workflows, while broader adult bands commonly span a few tens to a few hundreds of mg/dL depending on the assay (MedlinePlus Medical Encyclopedia, Quantitative Immunoglobulins). | low | Low IgA means IgA-class antibody tests may not light up even when disease is present. Celiac algorithms switch to IgG assays or biopsy. It also raises mucosal infection risk in some patients, so the plan is follow-up testing, not isolation of a single number. |
| Serum IgA (upper band or above) | Adult reference intervals often land near 40-350 mg/dL on many U.S. summaries, but your printed range wins (MedlinePlus lab test, Immunoglobulins Blood Test). | high | High IgA usually signals chronic antigenic stimulation—GI inflammation, alcoholic liver stress, chronic infection—or a proliferative immunoglobulin disorder. Clinicians layer protein electrophoresis, history, and organ tests rather than treating the count alone. |
| Serum IgA (borderline with conflicting symptoms) | Gray-zone results demand repeat on a new draw and comparison to prior baselines; hydration, acute illness, and assay drift all move immunoglobulins a few points (MedlinePlus lab test, Immunoglobulins Blood Test). | abnormal | Sitting just inside or outside the band with strong clinical story beats the lab header. Immunology consults trend levels over time and pair them with IgG, IgM, and specific antibodies so the picture is three-dimensional. |
When to Order
Celiac symptoms while relying on IgA-based serology
Before trusting a negative tTG-IgA, you need to know total IgA is sufficient. A sub-threshold total IgA forces IgG assays or biopsy planning so deficiency does not masquerade as reassurance.
Recurrent sinus, lung, or GI infections
Selective IgA deficiency is common and often silent, but it can line up with mucosal infections. Quantifying IgA is a first structural step when an immunologist is building a case for humoral insufficiency.
Chronic diarrhea, weight loss, or malabsorption
Inflammatory bowel disease and celiac disease both interact with IgA measurements. Total IgA frames whether IgA-class antibodies are even interpretable while the workup moves toward endoscopy or targeted panels.
Known monoclonal gammopathy or myeloma follow-up
Immunoglobulin quantification tracks clonal protein production. IgA myeloma exists; a climbing IgA with bone pain or renal clues triggers electrophoresis and specialist math, not panic from one line.
Unexplained high IgA with inflammatory symptoms
Elevation can follow chronic liver disease, alcoholic injury, or long-running mucosal inflammation. It is a breadcrumb that pushes the clinician toward organ imaging, stool workup, or rheumatologic screens rather than home diagnosis.
Prep & Logistics
- Fasting
- Follow lab instructions
- Sample
- Blood draw from a standard arm vein
- Results
- Usually 24-48 hours; many portals post the same day or the next.
- Referral
- Often self-order (check local rules)
- Markers
- Serum IgA concentration only. If celiac serology is the goal, clinicians usually pair total IgA with tTG-IgA or order an IgG-based backup when IgA is low.
Tests That Pair With This One
Bundles tTG and total IgA context the way gastroenterology algorithms expect when gluten-driven disease is suspected.
Adds the specific celiac antibodies once you know whether IgA-based testing is even valid.
Anemia, lymphocyte shifts, and platelet clues accompany many immunodeficiency and inflammatory presentations.
Liver synthetic markers and protein patterns help explain high immunoglobulins or malabsorption-driven losses.
When mucosal autoimmunity and systemic connective-tissue disease share the same symptom list, ANA is the wide net after immunoglobulin quantification.
FAQ
What is a normal IgA antibody level if I only see one IgA number?
You are looking at total serum IgA, not every possible IgA-class antibody. Normal bands are printed on your report and differ by lab and age. Compare to that interval, not a forum screenshot. If the result is low, celiac-specific IgA tests lose power and need IgG backups.
Is a high IgA level dangerous by itself?
Elevation is a clue, not a verdict. Chronic inflammation, liver stress, and long-running infections push IgA up. Danger lives in the clinical context: fever, weight loss, bone pain, or a spike on serum protein electrophoresis. Your clinician orders the next layer, not a single panic threshold.
Why would my doctor check IgA before a celiac blood test?
Total IgA deficiency makes tTG-IgA look falsely negative. Guidelines bake in a total IgA check—or simultaneous IgG testing—so you do not miss celiac because the wrong antibody class was quiet.
Do I need to fast for a serum IgA test?
Many immunoglobulin draws do not require fasting, but bundled orders might. Read the requisition: if lipids or glucose share the visit, fasting rules follow the strictest test. When unsure, call the draw site the day before.
Does this test tell me if I have IgA nephropathy?
No. IgA nephropathy is a kidney diagnosis built from urine blood, biopsy, and clinical course. Serum IgA can be normal or high and still misses the diagnosis. This draw measures quantity, not where immune complexes deposit.
Sources
GoodLabs pricing referenced below needs a live-site confirmation pass; immunoglobulin ranges summarized from MedlinePlus. Not generated by AI.
- GoodLabs - Immunoglobulin A (IgA) - Serum (pricing context)(verified 2026-03-23)
- MedlinePlus - Immunoglobulins Blood Test overview
- MedlinePlus Medical Encyclopedia - Quantitative immunoglobulins (interpretation context)
- Clinical context: LabRecon editorial team. Not medical advice. For informational use only.
IgA serum quantification. IgA deficiency (total IgA <7 mg/dL) causes false-negative IgA-based celiac antibody tests and increases susceptibility to mucosal infections.