Serum Immunoglobulin G (IgG) Subclass Analysis (Bromocresol Green Method)
This test measures the levels of different types of Immunoglobulin G (IgG), a key antibody protein in your immune system, using a specialized chemical method to detect each subclass.
["Understanding your IgG subclass levels helps identify immune system strengths or weaknesses."]
Key facts at a glance
- LOINC
- 81768-4
- Short code
- U1 snRNP70 IgG Ser IA-aCnc
- Synonyms
- U1 snRNP70 IgG Ser IA-aCnc
- Category
- chemistry
- 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
Why This Test Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms like frequent infections, autoimmune conditions, or if you’ve had a recent immune-related diagnosis. It can also help monitor immune function in certain chronic illnesses or after treatments like chemotherapy.
What to Expect Before the Test
No special preparation is needed. You’ll provide a blood sample, typically drawn from your arm. If you’re on blood thinners, let your provider know before the test.
What the Results Mean
IgG antibodies help fight infections, and each subclass plays a different role. Low levels in certain subclasses may suggest immune deficiencies, while high levels could indicate overactive immune responses or certain diseases. Your results will be interpreted by your healthcare provider in the context of your overall health.
Common Conditions Linked to IgG Subclass Levels
Abnormal IgG subclass levels can be linked to conditions like recurrent infections, autoimmune diseases (e.g., lupus, rheumatoid arthritis), or immune system disorders. Some treatments, like chemotherapy, can also affect IgG levels.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
IgG subclasses (IgG1, IgG2, IgG3, IgG4) test
Frequently asked questions
What questions might you have about this test?
How long will it take to get my results? Results are typically available within a few days to a week, depending on your lab.
What if my IgG subclass levels are out of range? Your healthcare provider will discuss your results with you and may recommend further testing or adjustments to your treatment plan.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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