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Immunoglobulin G (IgG) Subclass Quantification (Serum/Plasma)

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

This test measures the levels of different types (subclasses) of Immunoglobulin G (IgG), the most common antibody in your blood. IgG helps fight infections and is important for long-term immunity.

Quick summary

["IgG subclasses help doctors understand immune function and identify potential deficiencies or overactivity."]

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

Key facts at a glance

LOINC
17007-6
Short code
IgG Ser Ql
Synonyms
IgG 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

Why This Test Might Be Ordered

Your doctor may recommend this test if you have symptoms like frequent infections, autoimmune conditions, or if you’re being evaluated for immune-related disorders. It can also be part of monitoring for certain diseases or treatments that affect the immune system.

What to Expect Before the Test

No special preparation is usually needed. You may have a small needle inserted into your arm to draw blood. If you’re on blood thinners, let your doctor know before the test.

What the Results Mean

IgG is divided into four subclasses (IgG1, IgG2, IgG3, IgG4). Abnormal levels in any subclass may indicate immune system issues, such as low immunity, autoimmune diseases, or certain infections. Your doctor will interpret the results in the context of your health.

Common Conditions Linked to IgG Subclass Testing

Tests for IgG subclasses are often used to diagnose or monitor conditions like chronic infections, certain autoimmune diseases (e.g., lupus), or immune deficiencies. They may also help assess responses to vaccines or treatments like IVIG (intravenous immunoglobulin).

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Subclass Levels

Frequently asked questions

What does an abnormal IgG subclass result mean?
An abnormal result may signal an immune system issue, such as a deficiency in certain antibody types, which could make you more prone to infections. It may also point to autoimmune diseases or other conditions affecting antibody production. Your doctor will discuss the results with you and determine the next steps based on your symptoms and medical history.
How often should I get this test?
The frequency depends on your health condition and treatment plan. If you have an ongoing immune-related disorder, your doctor may recommend regular monitoring. For routine health checks, this test is usually not part of standard annual exams unless indicated by symptoms or risk factors.
Can lifestyle changes affect IgG subclass levels?
While diet and lifestyle factors can influence overall immune health, IgG subclass levels are primarily determined by your body’s immune response. However, maintaining a balanced diet, staying hydrated, and managing stress can support general immune function, which may indirectly benefit immune health.
  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