Allergy Asthma Technology Home Page

Tuesday, September 24, 2013

Diagnosing Allergies

Some allergies are easy to diagnose. If a bee sting causes hives, or petting a cat sets off a fit of sneezing, a person knows those are his or her allergens.  However allergic reactions do not always have obvious triggers, so it is a good idea to start taking notes on when, where, and under what circumstances problems occur.  More difficult cases require a physician's diagnosis.

A doctor will begin the examination by taking a personal and medical history, asking questions about the patient's family, medications, and lifestyle.  Any notes patients may have taken regarding their symptoms can help the doctor make an accurate diagnosis.

A physical examination will likely focus on the eyes, ears, nose, throat, chest, and skin – the places where allergies most often make themselves known. The physical may also include X-rays of the lungs and sinuses, and/or a pulmonary function test.

Skin tests, patch tests, and blood tests help the doctor determine a patient's allergens.

A skin test is often the least expensive and most accurate way to pinpoint allergens.  In the prick/scratch test, a small amount of the suspected allergen is placed on the skin which is then scratched or pricked with a needle.  Under the skin, or intra-dermal testing, requires a small drop of the allergen to be injected into the outer skin layer.

If the test site swells, turns red, begins itching, or develops hives, it is obvious the patient is allergic to the tested allergen.  Reactions occur within twenty minutes.

Contact dermatitis is diagnosed with a patch test in which a bit of the possible allergen is placed on the skin and covered with a bandage for 48 hours before checking to see if a rash has developed.

There are several types of allergen blood tests, including RAST (radioallergosorbent), FAST (fluorescent allergosorbent), MAST (multiple radioallergosorbent), RIST (radioimmunosorbent) and ELISA (enzyme-linked immunosorbent assays).  Blood samples are sent to a laboratory where they are mixed with suspected allergens to see how many antibodies the blood produces as a result.

Once the allergy tests are completed, patients can work with their doctors to find the best treatments for their allergies, whether it be medications, allergy shots, or just avoiding their allergy triggers.  Knowing is half the battle, so going through the diagnosis process is worth it to help ease the misery of allergies!