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Immunoglobulin A (IgA) in Serum or Plasma by Immunoassay

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of Immunoglobulin A (IgA), a type of antibody in your blood. IgA helps protect your body from infections by fighting bacteria and viruses.

Quick summary

["IgA helps defend against common infections and supports immune function."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
44389-5
Short code
IgA Ser Ql
Synonyms
IgA Ser Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What Does This Test Measure?

IgA is one of the key proteins in your immune system. It’s found in high concentrations in bodily fluids like saliva, tears, and mucus, but it also circulates in your blood. Measuring IgA helps doctors assess your immune response and identify potential deficiencies or overproduction that could affect health.

Why Might You Need This Test?

Doctors may order an IgA test to check for immune system issues, such as low levels that could increase infection risk or high levels linked to certain autoimmune conditions. It’s also used in diagnosing conditions like common variable immunodeficiency or monitoring immune responses in chronic diseases.

Common Reasons for Testing

Common reasons include evaluating symptoms like frequent infections, diagnosing immune disorders, or monitoring conditions like celiac disease or inflammatory bowel disease, where IgA plays a role in gut immunity.

What to Expect Before the Test

No special preparation is needed. A blood sample is taken from a vein in your arm, similar to other blood tests. If you’re on blood thinners, let your doctor know before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgA Level

Frequently asked questions

What does a low IgA level mean?
A low IgA level may suggest a condition called common variable immunodeficiency, where your immune system doesn’t produce enough antibodies to fight infections. It can also be linked to other immune disorders or certain genetic factors.
How often should I get this test?
Your doctor will determine how often you need this test based on your health history, symptoms, and diagnosis. Some people may need it once, while others may have it checked regularly if they have an ongoing condition.
Can IgA levels change with age?
Yes, IgA levels can vary with age. Infants and young children typically have lower IgA levels, which often increase as they grow older. In adults, certain health conditions, medications, or immune responses can also temporarily alter IgA levels.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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 16, 2026. · Read our editorial policy