Tests
1st tests to order
clinical diagnosis
Test
Usually no tests are necessary.
Result
features of dermatitis
Tests to consider
botanical identification
Test
Samples of suspect plants can be collected and sent for identification at local garden centers and botany schools. Avoid direct contact with the plants by wearing vinyl gloves (as urushiols can penetrate rubber or latex) and keep samples in sealed plastic bags. American Academy of Dermatology: poison ivy, oak, and sumac Opens in new window US Department of Agriculture: PLANTS database (search for: toxicodendron) Opens in new window CDC National Institute for Occupational Safety and Health: plant identification Opens in new window It is also possible to identify the presence of urushiols on leaves using leaf-spray mass spectrometry.[22]
Result
positive identification
black-spot test
Test
Wearing vinyl gloves (as urushiols can penetrate rubber or latex), place three to four leaves of the suspect plant in a folded sheet of white paper and crush against a hard surface, sufficient to create a wet spot on the paper. If positive, this spot should begin to turn dark after 10 to 15 minutes and becomes black after 24 hours, due to oxidation of the urushiols to become a lacquer.[2]
Result
positive result: dark spots begin to appear on paper after 10 to 15 minutes
Emerging tests
patch test
Test
A urushiol patch test using the TRUE test system (thin-layer rapid use epicutaneous). The safety, specificity, and sensitivity of the test is yet to be confirmed.[23]
Result
positive result: a local reaction; severity of reaction is correlated with dosage of urushiol used
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