Navigation Links
Memo to pediatricians: Allergy tests are no magic bullets for diagnosis
Date:12/25/2011

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.

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.


'/>"/>
Contact: Ekaterina Pesheva
epeshev1@jhmi.edu
410-502-9433
Johns Hopkins Medical Institutions
Source:Eurekalert

Related medicine news :

1. Allergy Sufferers Should Prepare for Holiday Triggers
2. Food Challenges Provide Best Allergy Diagnoses: Study
3. Improved Allergy Shots Might Be on Horizon
4. Dirt prevents allergy
5. A substance from bacteria can lead to allergy-free sunscreen
6. Next-generation allergy vaccines to be developed in Finland to create effective and safe desensitization therapies
7. Black Children May Be More Prone to Peanut Allergy, Study Finds
8. Switch to Powder-Free Latex Gloves Cuts Health Workers Allergy Risk
9. Longer Allergy Season Means More Misery
10. Using powder-free latex gloves reduces latex allergy rate in health care workers
11. Nut-allergy sufferers face prejudice -- new study
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:10/13/2017)... (PRWEB) , ... October 13, 2017 , ... Apple ... care services, staged a mock evacuation of the facility as part of a disaster ... Fire Department, Echo Hose EMS and Shelton City Emergency Manager, as well as the ...
(Date:10/13/2017)... , ... October 13, 2017 , ... Global Healthcare Management’s ... Alexandria Park in Milford, NJ. This free event, sponsored by Global Healthcare Management’s ... The fun run is geared towards children of all ages; it is a ...
(Date:10/13/2017)... ... October 13, 2017 , ... “The Journey: From the ... danger possible to save lost souls in the Philippines. “The Journey: From the Mountains ... a dedicated teacher of the Bible. She has taught all ages and currently teaches ...
(Date:10/12/2017)... ... October 12, 2017 , ... Planet Fitness, one of the largest and ... plans to open a flagship location in Covington, LA at 401 N. U.S. Highway ... store next to Office Depot in the Holiday Square shopping center. Its location allows ...
(Date:10/12/2017)... ... 2017 , ... Asante, a nationally recognized health system in ... existing home health joint venture through an agreement, effective October 1, 2017, to ... home health company with Asante, delivering clinically integrated care, for the past eight ...
Breaking Medicine News(10 mins):
(Date:10/10/2017)... -- NDS received FDA 510(k) clearance in May 2017 for its highly ... designed for endoscopy environments. An innovative secondary monitor solution, ZeroWire ... support the improvement of patient outcomes, procedural efficiency, and the lowering ... ... ...
(Date:10/4/2017)... 4, 2017  South Korean-based healthcare product Development Company ... "cprCUBE" on Kickstarter. The device will educate the user ... with better efficiency compared to the dated and pricey ... on efficacy of the compression for a more informed ... goal to raise $5,000. ...
(Date:10/2/2017)... 2017  Eli Lilly and Company (NYSE: ... third quarter of 2017 on Tuesday, October 24, 2017. ... day with the investment community and media to further ... call will begin at 9 a.m. Eastern time. Investors, ... webcast of the conference call through a link that ...
Breaking Medicine Technology: