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Dermatophagoides farinae-Specific IgG4 Antibody, Qualitative (RAST)

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

A qualitative blood test that detects IgG4 antibodies directed against the house dust mite allergen Dermatophagoides farinae.

Quick summary

["This legacy test detects house dust mite-specific IgG4, but it does not by itself confirm an allergy."]

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

Key facts at a glance

LOINC
26420-0
Short code
Deprecated D farinae IgG4 RAST Ql
Synonyms
Deprecated D farinae IgG4 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 test looks for IgG4 antibodies directed against Dermatophagoides farinae, a common house dust mite allergen. It is a qualitative RAST-style assay and appears to use a legacy or deprecated testing designation.

Why might I need this test?

It may have been used to assess the immune response to house dust mite exposure. Results are generally considered alongside symptoms, exposure history, and other allergy testing rather than being used alone to make a diagnosis.

How is the test performed?

A blood sample is collected and tested in the laboratory for antibodies to the house dust mite allergen. A qualitative result is generally reported as detected or not detected, depending on the laboratory's method.

How do I prepare for the test?

No special preparation is usually required, but follow the instructions provided by the ordering clinician or laboratory. Tell the healthcare team if you are taking biologic medicines or have recently had allergy testing, because these may affect some antibody tests.

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 mite IgG4 antibody test

Frequently asked questions

Does a positive result mean I am allergic to house dust mites?
Not necessarily. IgG4 antibodies can reflect exposure or immune tolerance, so a positive result must be interpreted with symptoms and other allergy evidence.
How is this different from house dust mite-specific IgE testing?
IgE testing is more closely associated with allergic sensitization, while IgG4 testing reflects a different immune response. Your clinician can explain which test is most useful for your situation.
Is this test still commonly used?
This appears to be a legacy or deprecated RAST-style test. Many clinicians prefer other standardized approaches for evaluating suspected house dust mite 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