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Immunoglobulin A (IgA) in Serum or Plasma

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

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

Quick summary

["IgA helps fight infections and supports immune function; low levels may indicate immune system issues."]

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

Key facts at a glance

LOINC
49907-9
Short code
IgA Ag Tiss Ql IF
Synonyms
IgA Ag Tiss Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 IgA Measure?

IgA is part of the immune system and is found in blood, saliva, and other bodily fluids. It plays a key role in protecting against infections by neutralizing pathogens. This test helps assess your immune response and detect potential deficiencies or abnormalities in IgA production.

Why Might You Need This Test?

Doctors may order an IgA test to investigate symptoms like frequent infections, autoimmune conditions, or to diagnose conditions such as common variable immunodeficiency (CVID). It can also be used in research or monitoring certain diseases.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The blood is then processed to measure the IgA concentration. This test is typically done using an immunoassay method to detect and quantify IgA accurately.

What Are Possible Results?

Results are reported as a concentration of IgA in the blood. There are no standard reference ranges provided here, as they can vary by lab and patient demographics. Your healthcare provider will interpret the results in relation to your symptoms and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

IgA Level

Frequently asked questions

What Are Common Causes of Low IgA Levels?
Low IgA levels can be caused by genetic conditions, certain autoimmune diseases, or conditions that affect the immune system, such as HIV/AIDS. Chronic infections, malnutrition, or certain medications may also lead to lower IgA levels. High IgA levels can sometimes be associated with certain autoimmune diseases or allergic reactions.
What Are Common Causes of High IgA Levels?
High IgA levels may be seen in conditions like autoimmune diseases, allergic reactions, or certain infections. They can also be a result of chronic inflammation or exposure to certain substances. Your doctor will consider your overall health and symptoms to determine the cause.
How Often Should I Get This Test?
The frequency of IgA testing depends on your medical condition and symptoms. If you have a known immune disorder or are under treatment for one, your doctor may recommend regular monitoring. Otherwise, this test is usually ordered as needed for specific concerns or investigations.
  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