Are you thinking about visiting an allergy center for an allergy test and wondering how do allergists test for allergies? There are plenty of ways they go about it with the common ones being:
Skin prick test (SPT)
It’s probably the most popular test you can have when you visit an allergy clinic. And the doctors love them for a reason—they are accurate and affordable.
Popularly known as SPT, the skin prick test is often carried out on the inner forearm but in some circumstances, it can be carried out on the other parts of the body such as at the back.
When you visit the clinic, the doctor places a small drop of allergen on your skin then pricks the skin with a lancet through the drop. If you are allergic to the allergens placed on your skin, you develop localized allergic response characterized by swelling, redness, and itching.
In most cases, the larger the wheal, the more likely you will be allergic to the allergen.
Intradermal skin test
This is a close cousin of the skin prick test and it consists of injecting a small amount of the allergen extract into your skin using a syringe and needle.
Doctors use this test when they suspect that you might be having allergies even after showing negative skin prick test results.
Allergy patch test
Also known as the epicutaneous test, this test is done to determine the allergen causing contact dermatitis and it’s performed by placing patches with different substances such as metals, foods, rubber chemicals and others on the skin of the back.
The doctor can place many patches depending on the substances that the doctor suspects you might be allergic to.
After the doctor has placed the patches on your back, he removes them after 48 hours then makes the reading after 72-96 hours.
If you are allergic to the substance placed on your back, you should develop a local rash.
You should note that immunomodulators and systemic corticosteroids can interfere with the results so always tell the doctor if using them.
Blood tests
There are two main types of blood tests that your doctor can undertake: total serum IgE or specific IgE.
The total IgE test measures all the IgE in the blood and it’s not often accurate as the IgE levels can be driven up by various factors such as skin diseases, virus infections, fungi, malignancies, and others.
The specific IgE test on the other hand is more accurate as it focuses on one individual allergen. The test is commonly used in children that are intolerant to skin allergies.
Here the doctor takes a blood sample and sends it to the laboratory. The lab then adds the allergen to the blood then measures the number of antibodies the blood produces to attack the allergens.
Oral food challenge test
This is a highly accurate diagnostic test for food allergies and doctors will undertake it after they have failed to get a definitive diagnosis even after performing the skin prick and blood tests.
During the test, the doctor feeds you the food he suspects you might be allergic to and observes you for a period. If there is a reaction such as flushing or hives, the allergy doctor Manassas VA will stop the test.
If there are no reactions after you have taken all the food, the doctor rules out food allergies.
If there is a reaction and the doctor confirms you are allergic to food, he will advise you on the foods to avoid and even prescribe the appropriate medications, often antihistamines to relieve the reactions.