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Parsley IgG Radioallergosorbent Test (RAST), Qualitative — Deprecated

Published: August 9, 2026Updated: August 17, 2026

A qualitative test for IgG antibodies to parsley using a RAST-type method. This deprecated test does not by itself diagnose food allergy.

Quick summary

["This historical test can show prior exposure to parsley, but a positive IgG result does not mean you have a parsley allergy."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
21444-5
Short code
Deprecated Parsley IgG RAST Ql
Synonyms
Deprecated Parsley 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 a qualitative laboratory test that looks for IgG antibodies directed against parsley. RAST stands for radioallergosorbent test. Because this test is deprecated, its availability and the exact reporting method should be confirmed with the laboratory.

Why might I need this test?

It may have been used to assess immune exposure to parsley or investigate a suspected food-related reaction. It is not a stand-alone diagnostic test for food allergy, and a clinician should interpret it alongside symptoms, medical history, and more appropriate allergy testing when needed.

How is the test performed?

RAST-type testing is generally performed on serum from a blood sample. The laboratory exposes the sample to parsley allergen and determines whether parsley-specific antibodies are present, usually reporting the result qualitatively.

How do I prepare for the test?

No special preparation is usually required, but you should follow the laboratory's instructions. Tell the clinician and laboratory about food allergies, recent reactions, and medications, and do not stop prescribed medicines unless your clinician advises you to do so.

Reference range

Adult: 10-40 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Parsley-Specific IgG

Frequently asked questions

Does a positive parsley IgG result mean I have a parsley allergy?
No. IgG antibodies commonly reflect exposure or immune tolerance and do not by themselves indicate an IgE-mediated allergy. Your clinician should interpret the result with your symptoms and history.
Why is this test described as deprecated?
It is an older testing approach that is no longer preferred for evaluating food allergy. Current allergy evaluation may use targeted IgE testing, skin-prick testing, or supervised food challenges when appropriate.
What should I do if this result is abnormal?
Discuss it with your clinician, especially if you have symptoms after eating parsley. The result may need to be interpreted alongside other allergy tests rather than treated as a diagnosis on its own.
  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 17, 2026. · Read our editorial policy