Allergy Testing (Skin Testing / RAST)

Allergy Testing:  an Important First Step Towards Treatment

Are you suffering from any of the allergy-related symptoms below?

• Runny nose
• Excessive sneezing
• Watery eyes
• Swelling

Are you unable to pinpoint the cause of your allergic attack? If so, you may benefit from allergy testing.

Dr. Cong Thu (CT) Nguyen is a Board Certified Ear, Nose and Throat specialist in Houston with extensive experience in the allergy field. Let Houston Sinus & Allergy help to place you on the road to recovery.

The Benefits of Allergy Testing

Allergy testing has been proven to greatly increase the standard of living for those who participate. Knowing what it is that one may have an adverse reaction to not only helps them prevent contact with the allergen in question, but also helps to begin a treatment regimen that could soften the affects of such foreign substances.

Is Allergy Testing Right for You?

Allergy testing involves having a skin or blood test to find out what substance, or allergen, may trigger an allergic response in a person.

Examples of allergens tested for as possible causes of type 1 hypersensitivity reactions are:

• Food allergies (i.e. peanuts, eggs, milk, seafood, etc.)
• Drugs (i.e. penicillin, etc.)
• Inhalant allergens (i.e.  pollens, house dust mite, cat and/or dog dander, etc.)
• Occupational allergens (i.e. latex, etc.)
• Venom (i.e. wasp, bee, etc.)

Skin Tests

A small amount of a suspected allergen is placed on or below the skin to see if a reaction develops. There are three types of skin tests:

Skin Prick Test

This test is done by placing a drop of a solution containing a possible allergen on the skin, and a series of scratches or needle pricks allows the solution to enter the skin. If the skin develops a red, raised itchy area (called a wheal), it usually means that the person is allergic to that allergen. This is called a positive reaction.

Intradermal Test

During this test, a small amount of the allergen solution is injected into the skin. An intradermal allergy test may be done when a substance does not cause a reaction in the skin prick test but is still suspected as an allergen for that person. The intradermal test is more sensitive than the skin prick test but is more often positive in people who do not have symptoms to that allergen (false-positive test results).

Skin Patch Test

For a skin patch test, the allergen solution is placed on a pad that is taped to the skin for 24 to 72 hours. This test is used to detect a skin allergy called contact dermatitis.

Radioallergosorbent  Testing (RAST)

Radioallergosorbent testing or RAST is a method employed in allergy testing (type 1 allergy – IgE mediated). The patient’s serum is incubated with a solid phase allergen and the amount of allergen-specific IgE quantified with radiolabelled anti-IgE. Many different allergens (e.g. house dust mite, grass pollen, cat epithelium) may be tested for with one sample of serum. Although the RAST was the first type of test described, radioisotopes are no longer used in the detection of specific IgE and hence the term RAST is now used as an abbreviation for an in vitro assay for specific IgE.

Where Can Houston Residents Get Allergy Relief?

At Houston Sinus & Allergy, we do a test (either through blood or the skin) to determine a patient’s allergy levels to the 70 most common respiratory allergens in the Houston area. Make an appointment with Dr. Nguyen today to determine if allergy testing is right for you, and get the relief you need.  You can either book an assessment or contact us today!