Antigen IgA (Serum) – Immunoglobulin A Level
This test measures the amount of Immunoglobulin A (IgA), a type of antibody in your blood. IgA helps protect your body from infections and plays a role in immune responses.
["IgA levels help identify immune function and potential deficiencies or disorders."]
Key facts at a glance
- LOINC
- 7105-0
- Short code
- ASPNID
- Synonyms
- A nidulans IgE Qn
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top vacutainer tube
- Units
- N/A
- Ref low
- 0
- Ref high
- 0.35
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–99 years
- Method
- Immunoassay (Fluorescent Enzyme Immunoassay or Chemiluminescent Immunoassay)
- CPT
- 86003
- SNOMED
- 395140007
- Specimen volume
- 1.0 mL serum (minimum 0.5 mL)
- Stability
- Room temperature: 8 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 100
- Lipemia max
- 200
- Icterus max
- 40
- TAT
- 24–72 hours
- Order
- routine
What Does This Test Measure?
IgA is one of the key proteins in your immune system. It’s found in blood, saliva, tears, and mucus. Low levels may suggest immune system issues, while high levels could indicate certain autoimmune conditions or infections.
Why Might You Need This Test?
Doctors may order this test if you have symptoms like frequent infections, chronic sinus issues, or if you’re being evaluated for conditions like common variable immunodeficiency (CVID) or certain autoimmune diseases.
Common Reasons for Testing
This test is often done when doctors suspect an immune system problem, especially in people who get sick easily or have digestive or respiratory issues. It can also be part of routine blood work for certain health conditions.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it involves drawing blood from a vein. Wear comfortable clothing and plan to stay near the testing site for a short time.
Reference range
Negative: <0.35 kU/L; Equivocal: 0.35-0.69 kU/L; Positive: 0.70-3.49 kU/L; Strongly Positive: 3.50-17.49 kU/L; Very Strongly Positive: ≥17.50 kU/LN/A
No special preparation required. Patient should inform clinician of any current antihistamine or corticosteroid use as these may affect IgE levels.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
IgA Antibody Test
Frequently asked questions
How low or high IgA levels might affect your health depends on your overall health and medical history. Very low IgA levels can weaken your immune defense, while very high levels may raise concerns about certain autoimmune disorders or infections.
What are the normal reference ranges for IgA levels?
Can IgA levels change with age?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 15, 2026. · Read our editorial policy