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Serum Immunoglobulin G (IgG) Level

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 antibodies play a key role in long-term immunity."]

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

Key facts at a glance

LOINC
77217-8
Short code
SP-1+CA6+PSP IgA+IgG+IgM Pnl Ser IA
Synonyms
SP-1+CA6+PSP IgA+IgG+IgM Pnl Ser IA
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
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 Is Done

Your healthcare provider may order this test if you have symptoms of a weakened immune system, such as frequent infections, low energy, or unexplained weight changes. It may also be checked before certain vaccines, to monitor immune function in chronic illnesses, or to evaluate conditions like autoimmune diseases or certain cancers.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood. The process usually takes a few minutes, and you can resume normal activities afterward.

What the Test Results Mean

Results are typically reported as a concentration level of IgG in the blood. While specific reference ranges vary by lab, lower than expected levels may indicate immune system issues, while higher levels might suggest conditions like multiple myeloma or certain infections.

Common Conditions Monitored

IgG levels are often checked in people with immune deficiencies, those receiving immune-suppressing treatments, or those with chronic illnesses like HIV/AIDS. It can also help diagnose or monitor conditions such as lupus, rheumatoid arthritis, or certain types of cancer.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

IgG is the most abundant antibody in the blood and provides long-term immunity. Low IgG levels may mean your body struggles to fight infections effectively, while very high levels could indicate overactive immune responses or underlying health concerns that need further evaluation.

Short name

IgG Level

Frequently asked questions

What causes IgG levels to be low?
Low IgG levels can result from immune system disorders (like hypogammaglobulinemia), certain medications, chronic illnesses, or genetic conditions. It may also appear in people who have had their immune system weakened by treatments like chemotherapy or organ transplants.
How long does it take to get test results?
Test results are usually available within 1–3 business days, depending on your lab and healthcare provider. Some labs may provide preliminary results sooner, but final interpretations are typically reviewed by a doctor.
Can diet affect IgG levels?
Diet alone does not significantly alter IgG levels, but maintaining a balanced diet rich in vitamins, minerals, and proteins supports overall immune function. Certain foods may indirectly influence immune health, but IgG is primarily measured through blood tests.
  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