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Deprecated House Dust-Specific IgG Antibody Test, Radioallergosorbent (RAST), Qualitative

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

A legacy blood test that looked for IgG antibodies to house-dust allergens and reported whether they were present. This test is now deprecated.

Quick summary

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

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

Key facts at a glance

LOINC
44380-4
Short code
Deprecated House Dust HS IgG RAST Ql
Synonyms
Deprecated House Dust HS 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 qualitative blood test looked for IgG antibodies directed against proteins found in house dust. It used a radioallergosorbent testing method, commonly called RAST, and is now considered deprecated.

Why might I need this test?

It was historically used to assess whether a person had been exposed to or sensitized to house-dust allergens. Most clinicians now use a clinical history and other appropriately validated allergy tests to evaluate suspected dust allergy.

How is the test performed?

A blood sample is collected, and the laboratory portion is tested with house-dust allergen in a RAST procedure. A labeled reagent is used to determine whether house-dust-specific IgG antibodies are present, with the result reported as positive, negative, or otherwise not detected.

How do I prepare for the test?

No special preparation is usually required for this type of blood test. Because it is deprecated, contact your healthcare professional before repeating the test to discuss whether a current allergy evaluation would be more useful.

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

House Dust-Specific IgG (RAST)

Frequently asked questions

Does a positive result mean I am allergic to house dust?
Not necessarily. The test detects IgG antibodies, which may reflect exposure or sensitization rather than a clinical allergy. Your clinician should interpret the result in the context of your symptoms.
Is this the same as a house-dust IgE allergy test?
No. This test looked for house-dust-specific IgG antibodies, while allergy evaluation commonly focuses on IgE antibodies, allergy skin testing, and the relationship between exposure and symptoms.
Why has this test been deprecated?
It is no longer routinely used because its clinical value is limited compared with a careful allergy history and other available testing. Ask your clinician about the most appropriate current alternative for suspected house-dust allergy.
  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