Skip to content

Serum IgG Substance Content (Qualitative or Quantitative)

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

This test measures the amount of Immunoglobulin G (IgG), the most common type of antibody in your blood. IgG helps protect your body from infections and diseases.

Quick summary

["IgG helps fight infections and supports immune function; low or high levels may indicate health concerns."]

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

Key facts at a glance

LOINC
35362-3
Short code
Trig in Chylo SerPl Ql
Synonyms
Trig in Chylo SerPl Ql
Category
glucose
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
true
Population
adult
Sex
all
Age range
18–65 years
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

What IgG Tests Measure

IgG is the primary antibody in your bloodstream, providing long-term immunity against bacteria and viruses. This test checks for its presence and concentration, which can vary based on immune response, health conditions, or medications.

Why It Matters in Your Health

IgG levels can be important for diagnosing or monitoring conditions like autoimmune diseases, infections, or immune deficiencies. Your doctor may order this test if you have symptoms of weakened immunity or if you’re being treated for an illness.

When You Might Need This Test

You may need an IgG test if you have recurring infections, chronic illnesses, or if your doctor suspects an immune disorder. It’s also sometimes checked during pregnancy, before vaccines, or after organ transplants.

What to Expect Before the Test

No special preparation is usually needed, but your doctor may ask you to fast for a few hours before the blood draw. A small needle will be used to collect a blood sample from a vein in your arm.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

Why might my IgG levels be checked?
Your IgG levels can help determine if your immune system is functioning properly. Low IgG might suggest an immune deficiency, while very high levels could indicate chronic infections, autoimmune diseases, or certain medications.
What do my IgG results mean?
Results are compared to a general range, but exact values depend on the test method and lab. Your doctor will interpret the results in the context of your health history and symptoms. Repeat testing may be needed if initial results are abnormal.
Can IgG levels change over time?
Yes, IgG levels can fluctuate due to infections, vaccinations, aging, or certain medical conditions. Regular monitoring may be recommended if you have a chronic illness or immune-related treatment.
  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