Featured Research

from universities, journals, and other organizations

Memo to pediatricians: Allergy tests are no magic bullets for diagnosis, experts say

Date:
December 26, 2011
Source:
Johns Hopkins Medical Institutions
Summary:
An advisory from two leading allergists urges clinicians to use caution when ordering allergy tests and to avoid making a diagnosis based solely on test results.

An advisory from two leading allergists, Robert Wood of the Johns Hopkins Children's Center and Scott Sicherer of Mt. Sinai Hospital in New York, urges clinicians to use caution when ordering allergy tests and to avoid making a diagnosis based solely on test results.

Related Articles


In an article, published in the January issue of Pediatrics, the researchers warn that blood tests, an increasingly popular diagnostic tool in recent years, and skin-prick testing, an older weapon in the allergist's arsenal, should never be used as standalone diagnostic strategies. These tests, Sicherer and Wood say, should be used only to confirm suspicion and never to look for allergies in an asymptomatic patient.

Test results, they add, should be interpreted in the context of a patient's symptoms and medical history. If a food allergy is suspected, Sicherer and Wood advise, the patient should undergo a food challenge -- the gold standard for diagnosis -- which involves consuming small doses of the suspected allergen under medical supervision.

Unlike food challenges, which directly measure an actual allergic reaction, skin tests and blood tests are proxies that detect the presence of IgE antibodies, immune-system chemicals released in response to allergens. Skin testing involves pricking the skin with small amounts of an allergen and observing if and how the skin reacts. A large hive-like wheal at the injection site signals that the patient's immune system has created antibodies to the allergen. Blood tests, on the other hand, measure the levels of specific IgE antibodies circulating in the blood.

These tests can tell whether someone is sensitive to a particular substance but cannot reliably predict if a patient will have an actual allergic reaction, nor can they foretell how severe the reaction might be, the scientists say. Many people who have positive skin tests or measurably elevated IgE antibodies do not have allergies, they caution. For example, past research has found that up to 8 percent of children have a positive skin or blood test for peanut allergies, but only 1 percent of them have clinical symptoms.

"Allergy tests can help a clinician in making a diagnosis but tests by themselves are not diagnostic magic bullets or foolproof predictors of clinical disease," Wood says. "Many children with positive tests results do not have allergic symptoms and some children with negative test results have allergies."

Undiagnosed allergies can be dangerous, even fatal, but over-reliance on blood and skin tests can lead to a misdiagnosis, ill-advised food restrictions or unnecessary avoidance of environmental exposures, such as pets.

In addition, the researchers caution, physicians should be careful when comparing results from different tests and laboratories because commercial tests vary in sensitivity. Also, laboratories may interpret tests results differently making an apples-to-apples comparison challenging, Wood says.

In their report, the scientists say, skin and blood tests can and should be used to:

  • Confirm a suspected allergic trigger after observing clinical reactions suggestive of an allergy. For example, children with moderate to severe asthma should be tested for allergies to common household or environmental triggers including pollen, molds, pet dander, cockroach, mice or dust mites
  • Monitor the course of established food allergies via periodic testing. Levels of antibodies can help determine whether someone is still allergic, and progressively decreasing levels of antibodies can signify allergy resolution or outgrowing the allergy
  • Confirm an allergy to insect venom following a sting that causes anaphylaxis, a life-threatening allergic reaction marked by difficulty breathing, lightheadedness, dizziness and hives
  • Determine vaccine allergies (skin tests only)

Conversely, skin and blood tests should NOT be used:

  • As general screens to look for allergies in symptom-free children.
  • In children with history of allergic reactions to specific foods. In this case, the test will add no diagnostic value, the experts say.
  • To test for drug allergies. Generally, blood and skin tests do not detect antibodies to medications.

Nearly 3 percent of Americans (7.5 million) and at least 6 percent of young children have at least one food allergy, according to the latest estimates from the National Institutes of Health.


Story Source:

The above story is based on materials provided by Johns Hopkins Medical Institutions. Note: Materials may be edited for content and length.


Journal Reference:

  1. Scott H. Sicherer, Robert A. Wood, and the Section On Allergy and Immunology. Allergy Testing in Childhood: Using Allergen-Specific IgE Tests. Pediatrics, 2011; 129 (1): 193 DOI: 10.1542/peds.2011-2382

Cite This Page:

Johns Hopkins Medical Institutions. "Memo to pediatricians: Allergy tests are no magic bullets for diagnosis, experts say." ScienceDaily. ScienceDaily, 26 December 2011. <www.sciencedaily.com/releases/2011/12/111226093350.htm>.
Johns Hopkins Medical Institutions. (2011, December 26). Memo to pediatricians: Allergy tests are no magic bullets for diagnosis, experts say. ScienceDaily. Retrieved December 22, 2014 from www.sciencedaily.com/releases/2011/12/111226093350.htm
Johns Hopkins Medical Institutions. "Memo to pediatricians: Allergy tests are no magic bullets for diagnosis, experts say." ScienceDaily. www.sciencedaily.com/releases/2011/12/111226093350.htm (accessed December 22, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Monday, December 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Christmas Kissing Good for Health

Christmas Kissing Good for Health

Reuters - Innovations Video Online (Dec. 22, 2014) Scientists in Amsterdam say couples transfer tens of millions of microbes when they kiss, encouraging healthy exposure to bacteria. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Brain-Dwelling Tapeworm Reveals Genetic Secrets

Brain-Dwelling Tapeworm Reveals Genetic Secrets

Reuters - Innovations Video Online (Dec. 22, 2014) Cambridge scientists have unravelled the genetic code of a rare tapeworm that lived inside a patient's brain for at least four year. Researchers hope it will present new opportunities to diagnose and treat this invasive parasite. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Americans Drink More in the Winter

Americans Drink More in the Winter

Buzz60 (Dec. 22, 2014) The BACtrack breathalyzer app analyzed Americans' blood alcohol content and found out a whole lot of interesting things about their drinking habits. Mara Montalbano (@maramontalbano) has more. Video provided by Buzz60
Powered by NewsLook.com
Touch-Free Smart Phone Empowers Mobility-Impaired

Touch-Free Smart Phone Empowers Mobility-Impaired

Reuters - Innovations Video Online (Dec. 21, 2014) A touch-free phone developed in Israel enables the mobility-impaired to operate smart phones with just a movement of the head. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins