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Immunoglobulin G (IgG) in serum, measured by nephelometry (total concentration)

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

This test measures the amount of Immunoglobulin G (IgG), a type of antibody in your blood. IgG helps protect your body from infections by fighting bacteria and viruses.

Quick summary

["IgG helps fight infections and supports long-term immunity."]

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

Key facts at a glance

LOINC
30489-9
Short code
Deprecated S pneum12 IgG sp2 Ser-mCnc
Synonyms
Deprecated S pneum12 IgG sp2 Ser-mCnc
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Is This Test Done?

Your healthcare provider may order this test to check for low or high levels of IgG, which can occur in conditions like immune deficiencies, chronic infections, or certain autoimmune diseases. It may also be used to monitor treatment responses or diagnose issues related to antibody production.

What to Expect Before the Test

No special preparation is usually needed. You may have a small needle inserted into a vein in your arm to draw blood. If you’re nervous, let your provider know so they can offer comfort measures.

What the Results Mean

IgG levels can vary based on health, age, and other factors. While specific reference ranges aren’t provided here, abnormal results may signal immune system problems or other health concerns that need further evaluation.

Common Reasons for Abnormal Results

Low IgG levels might indicate a weakened immune system, while very high levels could suggest chronic infections, certain cancers, or other conditions. Your provider will discuss these findings with you in detail.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What causes IgG levels to change?
IgG levels can be influenced by infections, immune system disorders, medications, or genetic factors. For example, newborns have lower IgG levels initially, which rise as they develop immunity. Chronic illnesses or treatments (like chemotherapy) may also affect these levels.
How often should IgG levels be checked?
Your provider will determine how often IgG testing is needed based on your medical history, symptoms, and treatment plan. Regular monitoring may be required if you have conditions like HIV, lupus, or other immune-related disorders.
Can diet or lifestyle affect IgG levels?
While diet and lifestyle factors like stress or sleep can influence overall health, they don’t directly alter IgG levels. However, maintaining a balanced diet and good health habits can support your immune system’s overall function.
  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