Test: Skin Prick Test - Dust Mite

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Background/Purpose

Dust mites – sometimes called bed mites – are the most common cause of allergy from house dust. Dust mites live and multiply easily in warm, humid places. They prefer temperatures at or above 70 degrees F with humidity of 75 to 80 percent. They die when the humidity falls below 50 percent. They are not usually found in dry climates.

Dust mite particles are often found in pillows, mattresses, carpeting and upholstered furniture. They float into the air when anyone vacuums, walks on a carpet or disturbs bedding, and they settle once the disturbance is over.

Dust mites are a common cause of asthma in children.

A house does not need to be visibly dirty to trigger a dust mite allergy reaction. The particles are too tiny to be seen and often cannot be removed using normal cleaning procedures. In fact, a vigorous cleaning can make an allergic person’s symptoms worse.

Procedure

The test area is cleaned and labeled using an appropriate skin marker. When multiple tests are being performed there should be a minimum of of 3cm between them. The skin is pricked lightly and quickly vertically through the sample allergen . A new micro lancet should be used for each substance being tested. The excess sample allergen should be removed immediately with an absorbent paper towel.
The wheals should be read after 15-20 minutes. For a positive reaction, the wheal should be >= 3mm in diameter. A valid result also requires a positive histamine reaction >=3mm and a negative saline control reaction of < 3mm.
Performed: Bilaterally

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Scratch test of grass allergen.

Criteria

• <3mm wheal
• No systemic reaction

Measurement

LOINC Code

Scale/Grading

selection range; grade - LOINC ID
Option - Value option selection range; grade - LOINC IDPass < 3 ; Pass - Equivocal = 3 ; Fail - Fail > 3 ; Fail -