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Serum IgG Subclass Detection by Line Blot (Qualitative)

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

This test checks for the presence of specific subclasses of Immunoglobulin G (IgG) antibodies in your blood, which may help identify certain immune system conditions or responses.

Quick summary

["This test helps doctors understand how your immune system is producing different types of antibodies."]

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

Key facts at a glance

LOINC
82932-5
Short code
sp100 IgG Ser Ql Line blot
Synonyms
sp100 IgG Ser Ql Line blot
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
line-blot
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?

IgG antibodies are the most common type of antibody in your blood and help fight infections. This test specifically looks for four subclasses of IgG (IgG1, IgG2, IgG3, IgG4) using a line blot method. Each subclass has a distinct role in immune function, and their presence or absence can provide clues about immune responses or disorders.

Why Might Your Doctor Order This Test?

Your doctor may recommend this test if you have symptoms or conditions linked to abnormal IgG subclass levels, such as recurrent infections, autoimmune diseases, or certain immune deficiencies. It can also be used to monitor treatment responses in patients with chronic immune disorders.

Sample Collection and Preparation

A blood sample is drawn from a vein, typically in your arm. The serum (liquid part of blood after clotting) is then tested using a line blot assay, which detects IgG subclasses visually on a test strip.

What to Expect Before the Test

No special preparation is needed for this test. You may have some mild discomfort or bruising at the injection site, but this usually fades quickly. If you are on blood-thinning medication, let your doctor know before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Subclass Screening

Frequently asked questions

What Are IgG Subclasses?
IgG subclasses are different forms of Immunoglobulin G antibodies that play specialized roles in your immune system. Each subclass has unique functions, such as helping fight infections or regulating immune responses. This test checks for the presence of these subclasses in your blood.
How Does This Test Differ from Other IgG Tests?
Unlike standard IgG tests that measure total antibody levels, this test specifically identifies IgG subclasses. It uses a line blot method to visually detect and confirm the presence of IgG1, IgG2, IgG3, and IgG4, which can provide more detailed information about immune function.
Can This Test Be Used to Diagnose Autoimmune Diseases?
While this test can help identify abnormal IgG subclass patterns that may suggest immune system imbalances, it is not a definitive diagnostic tool for autoimmune diseases alone. Doctors will often use this test in combination with other clinical findings, symptoms, and tests to make a diagnosis.
  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