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Deprecated Lemon-Specific IgG Radioallergosorbent (RAST) Test, Qualitative

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

A deprecated qualitative test for IgG antibodies to lemon. It is rarely used because food-specific IgG results do not establish clinical allergy.

Quick summary

["A positive result shows lemon-specific IgG, but it does not by itself confirm a lemon allergy."]

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

Key facts at a glance

LOINC
21364-5
Short code
Deprecated Lemon IgG RAST Ql
Synonyms
Deprecated Lemon 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 historical blood test intended to detect IgG antibodies directed against lemon. RAST stands for radioallergosorbent test; however, RAST is more commonly associated with IgE testing, so the laboratory should confirm the exact method used.

Why might I need this test?

It may appear in an older allergy-testing record or have been ordered previously to evaluate a suspected food reaction. It is deprecated and is generally not considered a current way to diagnose food allergy.

How is the test performed?

A blood sample is tested with lemon allergen using a laboratory method that detects a specific antibody class. Because this test is no longer current, the original laboratory method and report should be reviewed before interpreting the result.

How do I prepare for the test?

No special preparation is commonly associated with this test. Follow any instructions provided by the ordering clinician or laboratory, and do not stop eating lemon solely to change the result unless specifically directed.

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

Lemon-Specific IgG Test (Deprecated)

Frequently asked questions

Does a positive result mean I am allergic to lemon?
No. Food-specific IgG can occur without a clinical allergy, so a positive result alone does not establish that lemon causes your symptoms.
Why is this test marked deprecated?
The test is no longer considered a current or reliable way to diagnose food allergy. The laboratory can confirm whether the result is still relevant and suggest a more appropriate evaluation.
What should I do if I have symptoms after eating lemon?
Discuss the timing and type of your symptoms with a healthcare professional. Seek urgent care for trouble breathing, throat swelling, faintness, or another severe reaction.
  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