Barrier function parameters in various keratinization disorders: transepidermal water loss and vascular response to hexyl nicotinate.

In this study, we characterized the stratum corneum barrier function in 39 patients with various keratinization disorders (autosomal dominant ichthyosis vulgaris [ADI] [n = 7], X-linked recessive ichthyosis [XRI] [n = 6], autosomal recessive congenital ichthyosis [CI] [n = 10], dyskeratosis follicularis [Darier's disease; DD] [n = 8], erythrokeratoderma variabilis [EKV] [n = 8]), and 21 healthy volunteers, using two non-invasive methods: transepidermal water loss (TEWL) measuring outward transport of water through the skin by evaporimetry, and the vascular response to hexyl nicotinate (HN) penetration into the skin as determined by laser-Doppler flowmetry. Significantly increased TEWL values were found on the volar forearm in all three forms of ichthyosis, compared with the healthy control group, with the highest TEWL values in the CI group. The penetration of HN on the volar forearm was accelerated in patients with ADI, XRI and CI, as indicated by a shorter lag time (t0) between HN application and initial vascular response. However, differentiation between CI and the other ichthyoses was not possible by this method. When using both methods in DD and EKV, no differences compared with the healthy controls could be detected on the volar forearm, where the skin was principally unaffected; only the measurements from the affected skin on alternative sites demonstrated significantly increased TEWL values. In ADI and CI, however, normal-appearing skin also showed impaired values. We conclude that both TEWL and the vascular response to penetration of HN are suitable methods to monitor the skin barrier function in keratinization disorders, and are helpful in discriminating between these disorders.