NIAID Guidelines for Diagnosing a Food Allergy
An estimated 5% of children age 5 years and younger have food allergies, reports the National Institute of Allergy and Infectious Diseases (NIAID)*. In an effort to address this rising public health problem, NIAID worked with the American Academy of Allergy, Asthma & Immunology and other organizations to create food allergy guidelines.
The Guidelines for the Diagnosis and Management of Food Allergy in the United States were released in December 2010 and published as a supplement to the Journal of Allergy and Clinical Immunology. A committee of 34 professional medical organizations, groups and agencies helped to oversee its development. Consisting of 43 clinical recommendations, the guidelines are intended to aid physicians in diagnosing and managing patients with food allergies. Additionally, they help to inform parents about advised diagnostic tests, treatment and prevention.
Visit http://www.jacionline.org/article/S0091-6749(10)01566-6/fulltext for the complete food allergy guidelines.
You can also download the summary written for families, caregivers and patients.
Below, KFA's medical advisory team reviews important recommendations from the NIAID guidelines:
Dr. David Stukus reviews the the different types of food allergy tests used to diagnose food allergies. He explains the limitations of the tests and why someone may test "positive", but not actually be allergic. Dr. Stukus explains:
- Skin prick tests
- Blood or serum tests for specific IgE
- Oral food challenges
- Sensitization vs allergy
Dr. Stukus further explains about food allergy tests. In this video, he covers:
- The different types of food allergy tests and what they mean and what their limitations
- Blood specific IgE testing (ranges, classes, commercial panels)
- False positives and predictive values
- Do-it-yourself allergy kits and other controversial tests
- Oral food challenges
- Component IgE testing
- Patch testing for delayed reactions
- What about IgG?
- Eczema, eosinophilic esophagitis and other related allergic diseases
Oral food challenges are the "gold standard" for diagnosing food allergies. Nancy Polmear-Swendris, MEd, RN, explains the process of an oral food challenge and how parents and children can prepare for this important test.
There are times when a patient thinks they are reacting to a food or having symptoms as a result of eating certain foods. In these cases, food diaries – or, perhaps more accurately, symptom diaries – can be useful diagnostic aids. These simple records of what you eat and what symptoms you feel can help your doctor narrow down possible triggers, and in turn help you feel better.
Food Allergy Tests Alone Do Not Diagnose Food Allergies
NIAID Guideline #7 recommends specific IgE (sIgE) tests for identifying foods that potentially provoke IgE-mediated food-induced allergic reactions, but alone these tests are not diagnostic of Food Allergy.
“Testing for specific IgE to foods, through either skin or serum testing, is very helpful in diagnosing IgE-mediated food allergic reactions, but these tests should never take the place of a good history or possibly a food challenge,” said Todd D. Green, MD, assistant professor of pediatrics in the Division of Pulmonary Medicine, Allergy & Immunology at Children's Hospital of Pittsburgh of UPMC.
In general, a bigger skin test size or higher level of specific IgE in serum means that allergy is more likely, but the distinction between sensitization (positive skin test, or detectable specific IgE in serum) and clinical allergy (development of specific signs and symptoms of a reaction that develop after exposure) is very important to recognize. It is well-established that individuals may be sensitized, and therefore test "positive," but may not be clinically allergic.
This guideline also highlights the fact that there are differences between the systems used to measure specific IgE, so that values may differ depending on the system used, Dr. Green explained.
“Generally, if someone is tolerating a food, it is not necessary to perform any allergy testing to that food. Testing that is not indicated may lead to adverse consequences, such as unwarranted dietary changes, heightened anxiety and possibly adverse nutritional effects,” he said.
*The prevalence of food allergy quoted by NIAID was based on a 2007 study by the Centers for Disease Control. In 2011, Pediatrics published a study that found food allergy affects 8% of children in the United States.
Medical review July 2012.