[The sodium lauryl sulfate test. A noninvasive functional evaluation of skin hypersensitivity]

The purpose of this study was to determine whether 24 hour patch testing with 0.5% sodium lauryl sulphate (SLS) could reliably predict skin susceptibility to an irritant when compared with the alkali resistance test (ART), a widely used method employing sodium hydroxide. After having given informed consent, 40 patients (age range from 20 to 60 years) with an active irritant contact dermatitis (ICD), 40 patients in whom ICD had cleared, as well as 40 healthy volunteers serving as controls were tested. The skin responses to SLS were assessed both visually and by measurement of transepidermal water loss (TEWL) as an indicator of stratum corneum integrity. SLS significantly increased the erythema scores and TEWL in patients with healed ICD, and the increase of TEWL was even more pronounced in patients with active ICD. By contrast, a decrease in alkali resistance was found in patients with active ICD only but not in patients with healed ICD. The data obtained indicate that the SLS test, unlike ART, may provide a non-invasive tool predicting a possible constitutional skin susceptibility or indicating a subclinically impaired epidermal barrier function. However, because of the relatively high interindividual variation, a cut-clear statement concerning the skin susceptibility cannot be made by this test. On the other hand, the ART seems only to be useful for following and documenting the healing period following ICD.