Plasma Indirect Immunoassay for Immunoglobulin G (IgG)Medically reviewed by WellAlly Editorial Team·Last reviewed August 16, 2026·[Editorial policy](https://wellally.tech/editorial-policy)
## Key facts at a glance
LOINC73530-8Short codeamLODIPine ind plt IgM SerPl Ql FCSynonymsamLODIPine ind plt IgM SerPl Ql FCCategoryhematologySampleserumContainerRed-top tube (SST)UnitsN/AFastingfalsePopulationadultSexallAge range18–65 yearsMethodflow-cytometryCPT82784Specimen volume5 mLStabilityRoom temperature: 4h, Refrigerated: 24h, Frozen: 7dHemolysis max500Lipemia max1000Icterus max500TAT4–24 hoursOrderroutine
## 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, unexplained fatigue, or autoimmune conditions. It may also be used to monitor treatment responses in patients with certain immune-related disorders, like chronic infections or immune deficiencies.


## What to Expect Before the Test


No special preparation is usually needed. You may be asked to fast before the test, but this depends on the lab’s instructions. Bring any medications you’re currently taking to your appointment.


## How the Test Is Performed


A blood sample is drawn from a vein in your arm by a healthcare professional. The blood is then processed to separate plasma, which is tested for IgG subclass levels using an immunoassay method.


## What the Results Mean


IgG is the most abundant antibody in your blood, but it is divided into four subclasses (IgG1, IgG2, IgG3, IgG4). Each subclass has a different role in immunity. Abnormal levels may indicate immune system dysfunction, certain infections, or autoimmune diseases.


## Clinical interpretation


How abnormal results are interpreted and what conditions they suggest.


Abnormal IgG subclass levels can signal underlying health issues, such as immune deficiencies, chronic infections (e.g., HIV), or autoimmune disorders (e.g., lupus). Low levels of certain subclasses may indicate poor immune function, while high levels could suggest overactive immune responses or certain diseases. This test helps guide treatment decisions for conditions affecting antibody production or immune regulation.


## Short name


IgG Subclass Levels


## Frequently asked questions
What causes IgG subclass test results to be abnormal?IgG subclass test results may be abnormal due to immune system disorders (e.g., hypogammaglobulinemia), chronic infections, autoimmune diseases, or certain medications that affect antibody production. Your provider will discuss these findings with you based on your medical history and symptoms.How often should I get this test?The frequency depends on your health condition. If you have a known immune disorder, your provider may recommend regular monitoring. If this test is part of routine care, follow their guidance on timing.Can diet or medications affect IgG subclass levels?Some medications (e.g., steroids, chemotherapy) or certain health conditions (e.g., malnutrition) may influence antibody levels. Avoiding alcohol and certain supplements (like high-dose vitamins) before testing can help ensure accurate results.
## Sources
3
1. 1MedlinePlus — Laboratory TestsSource
2. 2Lab Tests OnlineSource
3. 3Mayo 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