FricTest® is a validated, easy to use dermographometer for diagnosing patients with symptomatic dermographism (urticaria factitia or dermographic urticaria) and for measuring their trigger thresholds and disease activity.
The comb-like, four-pronged design of FricTest® 4.0, the newest version of this instrument, allows for simultaneous dermal stimulation with four tips of different lengths exerting four different provocation levels, from I (the weakest) to IV (the strongest).
To obtain a response of dermographic urticaria, FricTest® is placed vertically so that the four tips are touching the skin, and then stroked once with moderate pressure across the width of the volar surface of the forearm (or the patient´s back) for a distance of approximately 6 centimeters.
A positive response is defined by a palpable weal of ≥ 3 mm in width (the diameter of FricTest® tips) at 10 min after provocation. Positive test responses to provocation with the longest FricTest® tip provocation level IV) confirm the presence of symptomatic dermographism.
Quick Facts FricTest®
Purpose: Confirm diagnosis of symptomatic dermographism and determine trigger thresholds (disease activity)
Suited for: Use by health care professionals or patients
Test sites: Volar forearm or back are recommended
Test reading: 10 minutes after provocation
Test result: Positive if wheal of ≥ 3 mm in width