British limrnai of Dermatology {1992) 1 26, 137-141. Friction* capacitance and transepidermal water loss (TEWL) in dry atopic and normal skin MARIE LODEN. HAKAN OLSSON.* TONY AXELL* AND YLVA WERNER LINDEt Kabi Pharmacia, Self Care. S-l I2H7 Stockholm. Sweden 'Department otOral Surgery and Oral Medicine. School of Dentistry. Carl Gustafs vag i4. S'2l4 21 Malmo. Sweden ^Department of Dermatology. Sodersiukhuset, S-1(HI 64 Stockholm. Sweden Accepted for puhlicatlon i September 1991 Summary Tbe biophysical properties of non-eczematous skin at three locations in atopies and non-atopies were characterized using non-invasive physical methods. Skin friction was measured witb a newly developed sliding friction instrument, the degree of hydration with a capacitance meter (Corneometer CM 820). and the transepidermal water loss (TKWI.) was determined using an Evaporimeter EPl. The areas examined (dorsum ofthe hand, volar forearm and lower back) sbowed lower values of friction and capacitance in the atopic patients than did corresponding sites in the normal controls. In most areas a significant correlation between friction and capacitance was found. The TEWL was increased in atopic skin, but TEWL seems to correlate neither to friction nor to capacitance. The tactile perception of the skin involves movement of a linger across tbe surface. The movement is restricted by friction. Thus, the frictional properties of tbe skin surface reilect aspects of the microtopograpby and are of importance for tbe evaluation ofthe skin. In normal skiti the frictional resistance varies for different anatomical regions, but not for age and sex.' Eriction increases with hydration."^ and with application of moisturizers."* Atopic dermatitis is a cbronic. relapsing and pruritic dermatitis that often involves tbe flexures of tbe body. In non~eczematous areas the skin can often be scaly and these areas feel rough and dry to tbe touch. (Ibjective measurements of tbe skin topography and hydration confirm this rough feeling"* and also its dryness.''•" Atopic skin shows an increased transepidermal water loss (TEWL). both In the rough and clinically normal skin and indicates a defective barrier function."'"' A significant part ofthe skin barrier function is provided by the stratum corneum lipids." whicb are believed to play a critical role in the water-retaining properties of the stratum comeum.'-" Recent findings suggest that the TEWL serves as a signal for an increased lipid synthesis after barrier damage.'' Tbe aim of this study was to examine the barrier function and surface features of non-eczematous atopic skin and to contrast these with those in normal skin, using non-invasive techniques. C«rrespondence: Dr Marie Loden. Methods Sttidy population Twenty-six subjects were included in the study after approval from the local Ethical Committee and the subjects' infonned consent. Eleven (nine women, two men. mean age 29 ±8 years) bad atopic dermatitis according to the criteria of Hanifin and Rajka.'"' They also had dry-looking skin (see below) at one or more of the three anatomical sites examined. The other iifteen subjects (nine women and six men; mean age 27±6 years) without any skin disease served as controls. The subjects were itistructed to refrain from using moistur- izers on the various sites for 5 days prior to the study. Evaluation 1 he study took place in the same room over 1 week in October. Tbe room temperature was 22-2-22-8°C and the relative humidity 4{}-5()%. The following three sites were studied: the dorsum of the hand, lower back and tbe volar part of tbe forearm. No areas witb eczema were studied and only the rough or clinically normal skin was examined. Prior to the measurements the appearance of the skin was graded clinically as follows: normal or smooth ( - ). rough with sligbt scaling (-I-). rougb with scaling {+ + ) and rough with marked scaling (+ -h +). The cliuical grading was done by one person (Y.W.L.). Tbe three measurements witb the diflerent techniques 137