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Serum/plasma concentration of immunoglobulin G (IgG) by immunoassay

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

This test measures the amount of Immunoglobulin G (IgG), a key protein in your immune system, found in your blood.

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
73152-1
Short code
Sildenafil cit ind plt IgM SerPl Ql FC
Synonyms
Sildenafil cit ind plt IgM SerPl Ql FC
Category
hematology
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
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 doctor may order an IgG test to check for low or high levels, which can happen due to immune system issues, certain diseases, or after treatments like chemotherapy. It may also be used to monitor immune function in conditions like HIV, autoimmune diseases, or after organ transplants.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or vein to draw blood. If you’re nervous, let your healthcare provider know so they can help make it more comfortable.

What the Test Results Mean

Results show your IgG level compared to what’s typical for healthy adults. Low levels may suggest weakened immunity, while very high levels could indicate certain immune disorders or chronic infections. Your doctor will interpret results in the context of your health history.

Common Causes of Abnormal Results

Low IgG levels can occur with conditions like HIV/AIDS, certain autoimmune diseases, or after treatments that weaken the immune system. High IgG levels may be linked to chronic infections, some cancers, or overactive immune responses.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What might cause my IgG test result to be different from usual?
Several factors can affect IgG levels, including chronic illnesses, recent infections, medications (like steroids), or even genetics. If your result is unusual, your doctor will review your medical history and other tests to understand why.
How often should I get this test?
Your doctor will decide how often you need this test based on your health needs. Some people get it once or twice a year, while others may need it more often if they have ongoing health conditions.
Can I eat or drink before this test?
You can eat and drink normally before the test, unless your doctor gives specific instructions. Avoiding alcohol or caffeine before the draw may help reduce stress, but it’s not required unless noted.
  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