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Immunoassay for Immunoglobulin G (IgG) Subclass 1 (IgG1) in Serum or Plasma

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

This test measures the amount of Immunoglobulin G (IgG) subclass 1, a key protein in your immune system, found in your blood.

Quick summary

["IgG1 helps fight infections and supports immune responses; levels can vary based on health and immune activity."]

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

Key facts at a glance

LOINC
12911-4
Short code
IGF-I 1.5h p chal SerPl-mCnc
Synonyms
IGF-I 1.5h p chal SerPl-mCnc
Category
hormone
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 healthcare provider may order this test to evaluate immune function, diagnose or monitor conditions like immunodeficiency, autoimmune diseases, or certain infections. It can also help assess how well your body is producing specific antibodies.

What to Expect Before the Test

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

What the Results Mean

Results are compared to a general reference range for healthy adults, but individual results can vary. Low levels may indicate immune deficiencies or certain infections, while high levels could suggest chronic inflammation or autoimmune conditions.

Common Conditions Monitored

IgG1 testing is often used alongside other immune tests to diagnose or track conditions like common variable immunodeficiency, HIV, or other antibody-related disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG1 Level

Frequently asked questions

What causes IgG1 levels to change?
IgG1 levels can be influenced by infections, chronic illnesses, immune system responses, or certain medications. For example, infections like COVID-19 or other viral/bacterial illnesses may temporarily alter antibody production.
How often should I get this test?
The frequency depends on your medical condition and provider’s recommendations. Some patients with chronic immune-related conditions may need monitoring every few months or annually, while others may only need it once.
Can diet or supplements affect IgG1 test results?
While diet and supplements may indirectly support immune function, they typically do not directly alter IgG1 levels. Focus on maintaining a balanced diet and following your provider’s advice for managing any related health conditions.
  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