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Serum/plasma mass concentration of immunoglobulin G (IgG) antibodies against a specific antigen (likely a protein or pathogen-related marker)

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

This test measures the amount of a specific antibody (IgG) in your blood, which may help identify immune responses to infections, vaccines, or other exposures.

Quick summary

["This test helps track immune responses and diagnose certain infections or conditions by detecting antibodies in your blood."]

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

Key facts at a glance

LOINC
17727-9
Short code
T palldm IgG Ser IF-aCnc
Synonyms
T palldm IgG Ser IF-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
if
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 of an infection, have been exposed to a pathogen, or if you’re being monitored for an immune-related condition. It could also be used after vaccination to check if your body produced the expected antibody response.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the draw if your blood is collected in the morning. Bring any medications or supplements you’re taking, as they may affect results.

How the Test Works

A small sample of your blood (either serum or plasma) is collected and analyzed to measure the concentration of IgG antibodies against a particular antigen. The method used may involve immunoassay techniques to detect and quantify these antibodies.

What the Results Mean

Results may indicate whether your immune system has produced detectable levels of the antibody. Elevated or low levels could suggest past exposure, vaccination success, or an ongoing immune response. Your provider will interpret results in the context of your symptoms and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

IgG antibody level (serum/plasma)

Frequently asked questions

What does a high or low IgG antibody level indicate?
High levels may indicate an active immune response, such as recovery from an infection or a successful vaccine response. Low levels could suggest immune deficiency, poor vaccine response, or chronic illness affecting antibody production.
Could this test detect a specific infection or disease?
Yes, this test can help identify whether your body has developed antibodies against certain pathogens (like viruses or bacteria) or foreign proteins. However, it may not detect active infection directly—your provider would use clinical symptoms and other tests for diagnosis.
Is fasting required for this test?
Fasting may be recommended for morning draws, but always follow your provider’s instructions. If you’re unsure, ask before your appointment.
  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