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Serum IgG Immunoglobulin Mass Concentration

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

This test measures the amount of Immunoglobulin G (IgG), a type of antibody in your blood serum. IgG is the most common antibody and plays a key role in defending against infections.

Quick summary

["IgG helps your immune system fight bacteria and viruses."]

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

Key facts at a glance

LOINC
43236-9
Short code
S pneum IgG Ser IA-mCnc
Synonyms
S pneum IgG Ser IA-mCnc
Category
coagulation
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

What Does IgG Measure?

IgG is the primary antibody produced by your immune system to protect against infections. It’s found in high levels in the blood and helps neutralize toxins and pathogens. This test helps doctors assess your immune response and identify potential deficiencies.

Why Might You Need This Test?

Your doctor may order an IgG test if you have symptoms of a weakened immune system, such as frequent infections, slow wound healing, or unexplained fatigue. It can also be used to monitor conditions like HIV, lupus, or other autoimmune diseases.

Sample Collection and Preparation

A blood sample is drawn from a vein in your arm. The blood is processed to separate the serum (the liquid part without clots) for testing. This test does not require fasting.

What to Expect Before the Test

There are no special preparations needed for this test. However, inform your doctor about any medications you’re taking, as some may affect blood test results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What Are Normal IgG Levels?
Normal IgG levels vary among individuals, and reference ranges can differ slightly between labs. Your doctor will compare your results to your baseline or specific clinical needs.
How Often Should I Get This Test?
Your doctor will determine the frequency based on your health condition and symptoms. Regular monitoring may be needed if you have an ongoing medical issue affecting your immune system.
Can Diet or Medications Affect IgG Levels?
Dietary changes or certain medications (like steroids or immune-modulating drugs) can influence IgG levels. Always discuss your medications and diet with your healthcare provider before interpreting results.
  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