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IgA Subclass Measurement (Serum)

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

This test measures the levels of Immunoglobulin A (IgA), a type of antibody in your blood that helps protect your body from infections.

Quick summary

["IgA helps fight respiratory, gastrointestinal, and skin infections; low or high levels may signal health concerns."]

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

Key facts at a glance

LOINC
7442-7
Short code
Firebush IgA Qn
Synonyms
Firebush IgA Qn
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 main antibodies your immune system produces. It appears in saliva, tears, mucus, and blood. This test specifically looks at the different subclasses of IgA, which can vary in function and may be relevant for certain immune-related conditions.

Why Might You Need This Test?

Doctors may order IgA subclass testing if you have symptoms like frequent infections, autoimmune diseases, or conditions affecting your immune system. It can also help diagnose or monitor conditions like IgA nephropathy or certain immune deficiencies.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The sample is then sent to a lab for analysis using an immunoassay method to measure IgA subclasses.

What Are Common Results?

Results are typically reported as concentrations of IgA subclasses (IgA1 and IgA2) relative to the standard units of measurement. These values help determine if your levels are within normal ranges or if further investigation is needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgA Subclass Levels

Frequently asked questions

What Are Possible Causes of Abnormal Results?
Low IgA levels may indicate an immune deficiency or certain autoimmune diseases. High IgA levels can sometimes be associated with chronic infections, certain cancers, or liver disease. Your doctor will consider your overall health and symptoms to interpret results.
How Often Should I Get This Test?
This test is usually ordered as part of a specific medical evaluation, such as diagnosing a condition or monitoring a known health issue. Follow your healthcare provider’s instructions for frequency.
What Should I Do If My Results Are Abnormal?
If your IgA subclass results are outside the expected range, your doctor may recommend additional tests or treatments based on your symptoms and medical history. Always discuss your results with a healthcare provider.
  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