Testing for Latex Allergy

by Food and Drug Administration (FDA)

(Page 2 of 3)

There are two ways to test for latex allergies. With one — the skin-prick test — tiny diluted amounts of latex or one of its proteins are injected under the skin or applied to a small scratch or puncture on the patient's arm or back. If the patient is allergic, a small, raised area surrounded by redness appears at the test site within about 15 minutes.

Laboratory analysis of a blood sample to detect antibodies is the other testing option. (The first time an allergic person is exposed to an allergen, the immune system produces a kind of antibody called immunoglobulin E — IgE for short.)

Slater says testing is both very important, and, unfortunately, imperfect. "It is clear that history alone is inadequate to screen some patients," he explains. (Some of the people who died from reactions to the latex barium enema tips had no history of latex allergy.) But, currently there is no FDA-approved extract for the skin-prick test or the blood test. Without an approved standard extract, the accuracy of the test results is not reliable.

The lack of an approved material that will identify latex-sensitive patients stems in part from latex's complexity. "We're comfortable that at least one of the proteins in latex is the problem," says FDA's Suleiman. But he adds that more than a dozen proteins have been identified in latex. "Which one of these actually initiates the [allergic] reaction? At this time, your guess is as good as mine."

He adds, however, that a tremendous amount of research has been stimulated by questions about latex's proteins.

In addition, latex from some sources, such as different brands of gloves, may cause more severe reactions than that from other sources, according to Harvard dermatology professor Ernesto Gonzalez in the February 1992 issue of the journal Hospital Practice.

Still, Slater says people in high-risk groups should be tested if they are concerned, as long as the tests are part of a through examination by an allergist who has the background to recognize possible allergens and exclude others based on an individual's history of allergic reactions. "It requires a fair amount of detective work," he says.

In addition, the allergist should be prepared with emergency equipment in case the skin-prick test itself causes a severe allergic reaction.

Slater warns that people shouldn't try to test themselves, by, for example, blowing up a latex balloon.

"That's a lousy idea," he says. "In fact, it's potentially very dangerous." He explains that a truly allergic person could go into shock from such a "test."

Finally, Slater says people who are not in a high-risk group and who haven't had any history of reactions "need to sit tight."

Suleiman agrees. "Right now, unless someone is already sensitive [to latex] there's no reason to discontinue use. We especially don't want to scare people away from latex condoms."

While approximately 1 billion to 2 billion condoms are used per year in the United States, FDA has received only 44 reports of allergic reactions associated with condom use between October 1988 and the end of 1991.

Latex Free

Surgery is nothing new for 7-year-old Paul Reynolds, of Herndon, Va. He was born with spina bifida, and last September's hip operation was his eighth. But, unlike the previous seven, this was his first surgery since he had developed an allergy to latex.

Paul's mother, Adriana Reynolds, says the doctors assured her the surgery would be latex free "as much as possible. I used to worry about the risks of anesthesia, but now I think this rubber allergy is my greatest concern."

Latex-containing devices fill the average surgical suite, and sometimes even medical professionals aren't aware that a device has a latex component.

"What is needed in the anesthesia world is a list of devices that don't have latex," says Jane McCarthy, a nurse-anesthetist and member of FDA's latex task group. "The clinicians can only attempt at best to provide an environment that's latex free. There's been difficulty in doing that because the devices aren't labeled with or without latex."

In response to that need, several hospitals have developed their own lists of latex-free devices. In addition, two nurse-anesthetists, Charles R. Barton and Cynthia A. Roy, have developed a list of commonly used medical devices that contain latex. (See accompanying chart).

To make sure a patient's latex allergy isn't overlooked, FDA sent a medical alert to approximately 1,000 leaders of health professional organizations in March 1991. The alert advised health professionals to:

Include questions about latex sensitivity when taking a patient's health history. (Asking patients if they've ever experienced itching, rash or wheezing after wearing latex gloves or inflating a toy balloon may be useful.)

Flag the charts of patients who report signs of latex allergy

Counsel patients who have a suspected latex-related allergic reaction while under the professional's care, and recommend a latex allergy test to those individuals.

The agency also recommended that when health professionals are treating a latex-sensitive patient, they should wear a non-latex glove over a latex glove. If both the health professional and patient are sensitive, triple-gloving — wearing a glove liner or vinyl glove under a latex glove as well as a vinyl glove over the latex — is recommended.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.