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Immunoglobulin G (IgG) Subclass 2 Concentration (Serum)

Published: August 9, 2026Updated: August 17, 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 part of your immune system.

Quick summary

["IgG2 helps protect against certain bacteria and viruses, and low levels may indicate immune system challenges."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
102836-4
Short code
Turkey IgG RAST
Synonyms
Turkey IgG RAST
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
rast
CPT
84484
SNOMED
302774002
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 types of bacteria and some viruses. IgG2 antibodies are particularly important for responding to infections like respiratory or gastrointestinal illnesses.

Why Might You Need This Test?

Doctors may order an IgG2 test if you have symptoms or conditions linked to immune system issues, such as recurrent infections, certain autoimmune diseases, or if you’re being evaluated for immune-related disorders. It can also be part of a broader evaluation for conditions like common variable immunodeficiency (CVID).

What Does a Low or High IgG2 Level Mean?

Low IgG2 levels may suggest a weakened ability to fight certain infections, especially those caused by bacteria like *Streptococcus* or *Haemophilus*. Very low levels could be associated with conditions like CVID. High IgG2 levels alone are less common but might be seen in certain immune responses or rare genetic disorders.

How Is This Test Done?

A blood sample is drawn from a vein in your arm. The sample is sent to a lab where it is processed to measure the IgG2 concentration using a specialized immunoassay method. Results are typically available within a few days.

Reference range

Adult: 10-40 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG2 Level

Frequently asked questions

Why might my doctor ask about IgG2 levels?
Your doctor may check IgG2 levels if you have a history of frequent or severe infections, unexplained fatigue, or symptoms that suggest an immune disorder. For example, if you’ve had repeated ear infections, pneumonia, or sinusitis, IgG2 testing could help assess whether your immune system is functioning as expected.
What are the most common reasons for abnormal IgG2 results?
Abnormal IgG2 results—either low or high—are less common than other IgG subclasses. Low IgG2 is more frequently associated with conditions like CVID, where the immune system produces insufficient antibodies overall. High IgG2 levels can sometimes be seen in certain immune responses or in rare genetic conditions, but they’re not typically a standalone concern unless part of a broader evaluation.
Can IgG2 levels change over time, and what affects them?
IgG2 levels can fluctuate due to infections, vaccinations, or certain medications that affect the immune system. Chronic illnesses, aging, or immune-suppressing treatments (like some cancer therapies) may also influence IgG2 concentrations. If your levels change, your doctor may recommend follow-up testing to understand the cause.
  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 17, 2026. · Read our editorial policy