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Serum or plasma mass concentration of immunoglobulin G (IgG) by nephelometry

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 and diseases.

Quick summary

["IgG levels help doctors assess your immune system’s strength and check for conditions affecting antibodies."]

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

Key facts at a glance

LOINC
27018-1
Short code
M-IgG Ser Ql
Synonyms
M-IgG Ser Ql
Category
chemistry
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 This Test Might Be Ordered

Your doctor may recommend this test if you have symptoms like frequent infections, low energy, or if you’re being treated for an immune-related condition. It can also be part of routine checks for people with certain medical conditions, like HIV or autoimmune diseases.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, usually drawn from your arm. If you’re on blood thinners, let your doctor know before the test.

What the Results Mean

Results show your IgG level compared to a general range. Very high or very low levels may signal health issues, but exact values depend on your health and medical history.

Common Conditions Affecting IgG Levels

Low IgG levels might indicate weakened immunity, while high levels could be linked to chronic infections, certain cancers, or overactive immune responses. Your doctor will interpret results in the context of your health.

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 be unusually high or low?
IgG levels can change due to infections, immune system disorders (like lupus or rheumatoid arthritis), certain cancers, or medications. Chronic illnesses, aging, or genetic factors may also play a role.
How often should I get this test?
Your doctor will decide based on your health needs. Some people get it yearly, while others need it more often if they have ongoing conditions affecting immunity.
Can diet or lifestyle affect IgG levels?
While diet and lifestyle can influence overall health, IgG levels are primarily measured in blood and are less directly affected by daily habits unless you have a specific immune-related condition.
  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