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Allergy Diagnostic Procedures and Treatment

Allergy Diagnostic Procedures and Treatment

Diagnostic tests for allergy may include any of the following:

Skin Tests

Skin testing is a very common and reliable test to determine your child’s allergies. Using small amounts of solution that contain different allergens, your child's doctor will either inject under the skin or apply the allergens on the surface of the skin with a small prick. A positive reaction will appear as a swollen area with redness around it at the site of the test in about 15 minutes. A reaction to the skin test does not always mean your child is allergic to the allergen that caused the reaction. Your child’s doctor will determine this. However, a non-reactive skin test is a reliable sign that your child is NOT allergic to that substance.

Blood Tests

Blood tests for allergies measure the antibody that causes allergic reactions, called IgE antibody, to specific allergens in the blood. The blood test most commonly used is called ImmunoCAP. Blood tests may be used when skin tests cannot be performed, or in addition to skin tests to give further information about the allergies. As with skin testing, it is important to remember that a positive blood test does not always mean your child is allergic to that allergen.

Graded Oral Food Challenge

This is a test to find out whether a person is allergic to a food. The food challenge is done in the Allergy Clinic or in the hospital. Medicines are ready to reverse a reaction if it occurs, and the doctor and nurse watch the patient carefully. The challenge starts with a very small amount of the suspected food allergen, and the patient is observed for a period of time. If there is no reaction, a slightly larger amount of the food is given and the patient is again observed for any reaction. The oral challenge proceeds until a full serving of food is eaten, or until there is an allergic reaction. It is rare for a severe allergic reaction to occur to an oral food challenge, because of the very small initial dose and very gradual increase in dose. Food challenges are done if it is unclear whether a patient is allergic to the food in question, or when a previous food allergy seems to be resolving. 

Oral Immunotherapy

Oral immunotherapy (OIT) is a process of building up tolerance to a food your child is allergic to. The goal of OIT is to decrease your child’s sensitivity to the food allergen. By slowly introducing the food allergen, it may lower the risk of life-threatening allergic reactions. The process is also known as desensitization.

The first step in this process is to find a safe starting amount of the food for your child. During your clinic visit, the doctor will identify the right dose your child can tolerate without having allergy symptoms. Your child will then take this small amount of the food every day at home. The dose slowly increases at clinic visits. Your child will get a slightly larger amount of the food, and you will give the new dose each day at home until your doctor gives you other instructions.

Your child is a good candidate for OIT if:

  • We can find a safe starting dose of the food allergen for your child.
  • They can cooperate with eating the food every day.
  • You are willing to make sure your child gets their dose of the food allergen every day. 
  • You can come for clinic visits every two to four weeks for roughly six months or longer, depending on how the process goes with your child.

Drug Allergy Testing

For patients suspected to have a medicine allergy, allergy skin testing is sometimes helpful to see whether they are allergic to the medicine. In many cases, a “test dose” of the medicine is given to see whether the patient is allergic to it. This is done in the Allergy Clinic or in the hospital, depending on the nature of the previous reaction and the state of general health of the patient. As with the graded oral food challenge, drug allergy test dosing usually starts with a low dose of the medicine, and the amount is gradually increased if the patient has no reaction during a period of observation. The physician and nurse watch the patient carefully, and medicines are available to reverse any reaction that occurs.   

Pulmonary Function Testing

This testing measures how well the lungs are working. Pulmonary function testing is often done for children with asthma, to monitor how well their asthma is controlled. It is also done to diagnose asthma or other respiratory problems. Children around 6 years old or older are usually able to perform pulmonary function testing. 

Last Updated 03/2018

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