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Immunoglobulin G (IgG) Subclass 3 Blood Mass Concentration by Nephelometry

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

This test measures the amount of a specific type of antibody (IgG3) in your blood. Antibodies help fight infections and are part of your immune system.

Quick summary

["IgG3 helps protect against certain bacteria and viruses, and levels can be checked for immune-related conditions."]

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

Key facts at a glance

LOINC
106807-1
Short code
IgG3 BldCo Neph-mCnc
Synonyms
IgG3 BldCo Neph-mCnc
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
nephelometry
CPT
82784
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your doctor may recommend this test if you have symptoms of an immune system disorder, such as frequent infections, autoimmune conditions, or if you’re being evaluated for conditions like chronic infections, certain cancers, or immune deficiencies. It may also be used to monitor treatment responses in patients with immune-related diseases.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw a blood sample. If you’re on blood thinners or have a history of bleeding issues, let your doctor know before the test.

What the Test Results Mean

IgG3 levels can vary based on health, age, and immune status. Abnormal results may indicate immune system issues, but they don’t diagnose a condition alone. Your doctor will interpret results in the context of your overall health and symptoms.

Common Conditions Monitored or Diagnosed

IgG3 levels are sometimes checked in patients with chronic infections (e.g., tuberculosis, HIV), autoimmune diseases (e.g., lupus, rheumatoid arthritis), or immune deficiencies. Low levels may suggest a weakened immune response, while high levels could be linked to certain immune disorders or overactive immune reactions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG3 Level

Frequently asked questions

What does a low IgG3 level mean?
A low IgG3 level may indicate an impaired immune response, which could be due to an immune deficiency, chronic illness, or certain medications that affect antibody production. Your doctor will consider other factors, such as your medical history and symptoms, to determine if further evaluation is needed.
What does a high IgG3 level mean?
High IgG3 levels are less common and may be associated with certain immune disorders, chronic infections, or autoimmune conditions. Your doctor will review your results alongside other tests and symptoms to understand the cause.
How often should I get this test?
The frequency of this test depends on your medical condition and treatment plan. If you’re being monitored for an ongoing immune-related issue, your doctor may recommend periodic testing to track changes in your IgG3 levels.
  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