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Immunoassay for Immunoglobulin G (IgG) in plasma or serum

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 is important for long-term immunity.

Quick summary

["IgG levels help assess immune function and identify deficiencies or excesses that may affect your health."]

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

Key facts at a glance

LOINC
88245-6
Short code
CARBIMP-PCR
Synonyms
blaIMP Bld Pos Ql Probe
Category
chemistry
Sample
whole-blood
Container
Positive blood culture bottle (aerobic or anaerobic) flagged positive by continuous-monitoring blood culture system (e.g., BACTEC, BacT/ALERT); aliquot transferred to sterile screw-cap tube or manufacturer-provided molecular assay cartridge/tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe
CPT
87150 (Culture, typing; identification by nucleic acid probing); 87798 (amplification probe) may also apply depending on billing
SNOMED
715272007 |Detection of carbapenem resistance gene (procedure)|; or 1177176009 |Carbapenem-resistant organism screening (procedure)|
Specimen volume
1-2 mL aliquot from positive blood culture broth (per assay manufacturer specifications)
Stability
Test as soon as possible after blood culture positivity is flagged. Blood culture broth stable at room temperature (20-25°C) for up to 24 hours post-positivity. Refrigerated (2-8°C) storage acceptable for short delays; freezing generally not recommended unless specified by assay.
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
1–8 hours
Order
routine

What Is Immunoglobulin G (IgG)?

IgG is the most common type of antibody in your blood. Antibodies are proteins that help your immune system fight infections and diseases. IgG provides long-lasting protection by staying in your bloodstream longer than other antibodies.

Why Might You Need This Test?

Doctors may order an IgG test to check for immune system issues, such as low levels (hypogammaglobulinemia) that can make you more prone to infections, or high levels that might indicate certain medical conditions like multiple myeloma or autoimmune diseases.

Common Reasons for Testing

Common reasons include diagnosing or monitoring conditions like recurrent infections, immune deficiencies, or certain cancers. It may also be used in newborns to check for inherited immune disorders or in people with chronic illnesses like HIV or lupus.

Sample Collection and Preparation

This test uses a blood sample drawn from a vein in your arm. The blood is processed into either serum (after clotting) or plasma (using an anticoagulant). The sample is then sent to a lab for analysis using an immunoassay method to detect IgG antibodies.

Reference range

Negative (blaIMP gene not detected)N/A

Specimen: whole-blood

No special patient preparation required. Sample is collected from a positive blood culture bottle, not directly from patient. Verify patient identity and blood culture bottle labeling before submission to molecular testing.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance of IgG Levels

Short name

IgG Level

Frequently asked questions

What Does an Abnormal IgG Level Mean?
Low IgG levels may suggest an immune deficiency, where your body struggles to produce enough antibodies to fight infections. High IgG levels could indicate chronic inflammation, certain cancers, or autoimmune diseases that cause the body to produce excessive antibodies.
How Often Should I Get This Test?
The frequency depends on your health condition and why the test was ordered. Your healthcare provider will determine how often you need retests, especially if you have an ongoing medical issue like an immune deficiency or cancer.
Can Diet or Supplements Affect IgG Levels?
Diet and supplements generally do not directly affect IgG levels, as IgG is produced by your immune system. However, maintaining a balanced diet supports overall immune health, which may indirectly benefit your immune function.
  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