Skin pH and its relationship with transepidermal water loss and disease severity in children with atopic dermatitis: A cross-sectional study

Background: pH is increasingly a target in therapeutic strategies for skin barrier repair, but the relationship between pH, transepidermal water loss (TEWL), and atopic dermatitis (AD) severity is not well characterized. Purpose: The purpose of the study was to determine the relationship between skin pH with TEWL and their correlations with AD severity. Methods: A cross-sectional study enrolled children aged 4–12 years with AD. Measurements were made using HI 99181 and Tewameter TM 300 at two lesional sites and two nonlesional sites (left cubital fossa, left thigh, and forehead). Disease severity was evaluated using the Eczema Area and Severity Index (EASI) and pruritus score. Results: A total of 14 (58%) girls and 10 (42%) boys aged 7.3 ± 2.6 years with age of AD onset 3.0 ± 2.1 years participated. The mean EASI score was 8.9 ± 8.2, body surface area 13.1% ± 18.5%, pruritus score 5.9 ± 2.7, and Children Dermatology Life Quality Index 5.6 ± 4.9. pH and TEWL were higher at lesional compared to nonlesional skin, pH 5.2 ± 0.7 versus 4.6 ± 0.4, P < 0.01 and TEWL 31.1 ± 15.2 versus 16.0 ± 10.2, P < 0.01. Lesional pH positively correlated with TEWL (r = 0.59, P= 0.02 and r = 0.55, P = 0.01), while nonlesional pH was inversely correlated (r = −0.42,P = 0.04 and r = −0.40, P = 0.05). pH showed significant positive correlations with EASI and itch at one lesional site. Conclusion: pH and TEWL were higher at lesional skin. pH correlated positively with TEWL at lesional skin but inversely at nonlesional areas. Higher pH was associated with disease severity and itch. pH restoration may have therapeutic potential in AD.