Skip to content

Immunoglobulin G (IgG) Subclass 3 Quantification (Serum/Plasma)

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

This test measures the amount of Immunoglobulin G (IgG) subclass 3 in your blood, which is a type of antibody that helps fight infections and diseases.

Quick summary

["IgG3 helps protect against certain bacteria and viruses, and levels can be checked if you have immune-related conditions or symptoms."]

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

Key facts at a glance

LOINC
94438-9
Short code
HLA-DRB3 + 4 + 5 IgG SerPl FC
Synonyms
HLA-DRB3 + 4 + 5 IgG SerPl FC
Category
chemistry
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 Might Be Ordered

Your healthcare provider may order this test if you have symptoms like frequent infections, autoimmune conditions, or if you’re being treated for a condition that affects your immune system. It could also be part of monitoring for certain immune disorders or before receiving certain immunizations.

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

IgG3 levels can vary based on your health, age, and immune status. Low levels might suggest immune deficiency, while high levels could indicate chronic infections or certain immune responses. Your provider will discuss results with you in the context of your overall health.

Common Conditions Monitored

IgG3 levels are often checked in people with conditions like chronic infections (e.g., tuberculosis), autoimmune diseases (e.g., lupus), or those receiving immune-modifying treatments.

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 might suggest an immune system that struggles to produce enough of this antibody, which could increase your risk of infections, especially those targeted by IgG3. This may require further evaluation to determine if it’s due to an underlying condition or just part of your natural immune response.
How often should I get this test?
Your provider will decide how often you need this test based on your health needs. Some people get it once, while others may need it periodically if they have ongoing immune-related conditions or treatments.
Can diet or supplements affect IgG3 levels?
Diet and supplements may indirectly influence immune function, but they don’t directly affect IgG3 levels. Focus on a balanced diet rich in vitamins and minerals to support overall immune health, but discuss any supplements with your provider first.
  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