Plasma IgG Radioallergosorbent (RAST) Test, Qualitative — Deprecated
An older qualitative plasma test for IgG-related reactivity using a RAST-style method. This test is deprecated and may no longer be available.
["This is a deprecated qualitative plasma antibody test, and its findings should be interpreted by a clinician."]
Key facts at a glance
- LOINC
- 21469-2
- Short code
- Deprecated Plum IgG RAST Ql
- Synonyms
- Deprecated Plum IgG RAST Ql
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 10
- Ref high
- 40
- Critical range
- — – 500 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84484
- SNOMED
- 302774002
- 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
What is this test?
This is an older laboratory test that evaluates IgG-related reactivity in a plasma sample. RAST stands for radioallergosorbent, a type of antibody testing method. The exact antibody target is not clear from the abbreviated test name.
Why might I need this test?
It may have been used to help identify a reaction to a specific substance or to assess immune-related activity. Because the test is deprecated and the target is not specified in its name, the original laboratory report and ordering clinician are important for interpretation.
How is the test performed?
A blood sample is collected, and the laboratory separates the plasma for qualitative antibody testing. The result is reported as detectable or not detectable, possibly with additional information supplied in the original report.
How do I prepare for the test?
Special preparation is generally not required for a routine antibody test. Follow any instructions provided by the ordering clinician or laboratory, particularly if the test is being used to evaluate a suspected allergy or immune condition.
Reference range
Adult: 10-40 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A detectable result may indicate that antibodies associated with the tested target are present, but its clinical meaning depends on the exact substance or condition being evaluated. Results can reflect prior exposure, vaccination, infection, or an immune disorder. Because this test is deprecated and its abbreviated name does not identify the target clearly, a clinician should interpret it alongside symptoms, history, and more specific current tests.
Short name
Plasma IgG RAST, Qualitative
Frequently asked questions
Is this test still available?
What does a qualitative result mean?
Does a positive result mean I am allergic?
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 17, 2026. · Read our editorial policy