October. 21 (HealthDay News) -- Adults and children who have allergy patch tests are equally likely to react to skin allergens, but they tend to react to different types of skin allergens, a new study finds.

Dr. Kathryn A. Zug, of Dartmouth-Hitchcock Medical Center in Lebanon, N.H., and her colleagues found rates of positive tests for at least one allergen were about the same among children (51.2 percent) and adults (54.1 percent). They compared 391 children under the age of 18 and 9,670 adults aged 19 and older.

However, the study found "significant differences between the frequency of individual positive reactions to allergen patch tests in children and adults; children were more likely to have reactions to nickel, cobalt, thimerosal and lanolin, whereas adults were more likely to have positive reactions to neomycin, fragrance mix, M. pereirae (balsam of Peru [an extract from the balsam tree used as an alternative therapy]) and quaternium 15," the researchers wrote.

They found that some children reacted to supplemental allergens not included in common patch test series (15 percent) or in commercially available tests (39 percent). Compared to adults, children with a positive reaction were more likely to have atopic dermatitis (reactions on skin not directly in contact with an allergen) included as one of their final diagnoses -- 34 percent vs. 11.2 percent.

The study was published in the October issue of the Archives of Dermatology.

"Patch testing in children suspected of having allergic contact dermatitis is a valuable endeavor. Despite their limited back size, an expanded allergen series helps to identify important positive relevant allergens. Allergen concentration does not need modification for testing in children," the researchers concluded. "The top 45 allergens with the most frequent positive and relevant reactions reported in this study should serve as a guide to patch testing in children suspected of having allergic contact dermatitis in North America. Including supplemental allergens to the patch test materials based on clinical suspicion is also useful in some patients."

SOURCE: JAMA/Archives journals, news release, Oct. 20, 2008