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Immunoassay for Immunoglobulin G (IgG) Subclass 1 (IgG1) Antibody Levels in Serum

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

This test measures the amount of Immunoglobulin G1 (IgG1), a type of antibody in your blood, which helps fight infections and supports immune function.

Quick summary

["IgG1 antibodies play a key role in immune defense; levels may vary based on health, immune response, or underlying conditions."]

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

Key facts at a glance

LOINC
73283-4
Short code
MTX ind plt IgG SerPl Ql FC
Synonyms
MTX ind plt IgG SerPl Ql FC
Category
hematology
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
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 Is Done

Your doctor may order this test to evaluate immune function, assess immune response to vaccines or infections, or investigate symptoms like recurrent infections, autoimmune conditions, or certain immune deficiencies.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, usually drawn from a vein in your arm. Tell your healthcare provider about any medications or conditions that might affect results.

What the Test Results Mean

Results may indicate normal immune function, an abnormal immune response, or potential issues like low antibody production (hypogammaglobulinemia) or overactive immune reactions. Your doctor will interpret results in the context of your health history.

Common Conditions Linked to IgG1 Levels

Changes in IgG1 levels can be associated with autoimmune diseases (e.g., rheumatoid arthritis), chronic infections, certain immune disorders, or responses to treatments like chemotherapy or monoclonal antibodies.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG1 Antibody Level

Frequently asked questions

What causes IgG1 antibody levels to be tested?
IgG1 testing is often done when symptoms like frequent infections, autoimmune reactions, or vaccine response issues are present. It may also be part of a broader immune evaluation for conditions like HIV, lupus, or congenital immune disorders.
How do IgG1 levels differ from total IgG levels?
IgG1 is just one subclass of IgG antibodies. Total IgG measures all IgG types combined, while IgG1 specifically targets only this subclass. Subclass testing helps identify specific immune dysfunctions that total IgG might not reveal.
Can diet or medications affect IgG1 levels?
Dietary factors like protein intake may indirectly support immune function, but they don’t directly alter IgG1 levels. Certain medications (e.g., steroids, chemotherapy) or immune-modifying treatments can influence antibody production, so discuss any medications with your doctor before testing.
  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