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Immunoglobulin G (IgG) Subclass 2 Serum Mass Concentration

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

This test measures the amount of Immunoglobulin G (IgG) subclass 2, a type of antibody in your blood. IgG antibodies help fight infections and are important for long-term immunity.

Quick summary

["IgG2 helps protect against certain bacteria and viruses, and low levels may affect immune function."]

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

Key facts at a glance

LOINC
6939-3
Short code
IgA2 Ser-mCnc
Synonyms
IgA2 Ser-mCnc
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?

IgG2 is one of five subclasses of Immunoglobulin G (IgG), the most common antibody in your blood. This test specifically looks at the concentration of IgG2, which plays a role in defending against specific pathogens. IgG2 antibodies are particularly important for responding to certain types of bacteria and some viruses.

Why Might You Need This Test?

Doctors may order an IgG2 test if you have symptoms of a weakened immune system, recurrent infections, or if you’re being evaluated for conditions like recurrent sinusitis, pneumonia, or other infections that don’t clear up easily. It can also be part of a broader immune evaluation.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The blood is then sent to a lab where it’s analyzed to measure the IgG2 concentration. The test doesn’t require fasting or special preparation.

What Are Possible Results?

Results are typically reported as a mass concentration (often in grams per liter or milligrams per deciliter). Your doctor will interpret the result in relation to your health and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: IgG2 Levels and Immune Function

Short name

IgG2 Level

Frequently asked questions

Why do I need this test?
Your doctor may recommend this test if you have frequent or severe infections, unexplained immune issues, or if you’re being treated for conditions like recurrent sinusitis, bronchitis, or other infections that don’t respond to standard treatments. Low IgG2 levels can sometimes indicate a deficiency in this antibody subclass, which may affect your body’s ability to fight certain infections.
What does a low IgG2 level mean?
A low IgG2 level may suggest a weakened immune response to specific bacteria or viruses. It doesn’t always mean you’re sick, but it can help identify potential immune challenges that might need further evaluation or treatment, such as immune therapy or monitoring.
How often should I get this test?
The frequency of testing depends on your medical condition and doctor’s recommendations. If you have a known immune disorder or are at risk for infections, your doctor may suggest regular monitoring. Follow-up testing is usually done based on clinical needs and responses to treatment.
  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