Epidermal Biophysical Characteristics in Patients with Vitiligo and the Association with Thyroid Auto-immunity and Itch.

ABSTRACT

Background: Vitiligo is characterized by depigmentation due to melanocyte destruction. Itch is an under-recognized symptom; its pathophysiology is unclear. Aims: To compare epidermal biophysical characteristics of the vitiligous skin and normal skin and to determine the association with thyroid auto-immunity and itch. Methods: A cross-sectional study involving vitiligo patients was conducted. Hydration, pH, and trans-epidermal water loss (TEWL) at the vitiligous skin and normal adjacent skin were measured. The Vitiligo Disease Activity Score (VIDA) and Vitiligo Area Scoring Index (VASI) were assessed. Itch severity and thyroid auto-antibodies were determined. Results: Thirty-nine (62.9%) females and 23 (37.1%) males participated. Twenty-six (41.9%) had stable vitiligo, and 36 (58.1%) had active disease with a median VASI was 0.8 (2.2). Hydration was lower [93 (83) to 125.5 (111) vs 104 (73) to 156 (100), P < 0.01] and TEWL [7.13 (6.18) to 8.86 (6.93) vs 5.54 (5.90) to 6.88 (6.37), P < 0.01] was higher at the vitiligous skin compared to the normal skin. A non-significant higher pH trend was observed in the vitiligous skin. Thyroid antibody was detected in 19.7% patients. There were no significant differences in biophysical characteristics between patients with and without thyroid antibodies, with hydration of 88 (159) to 129.5 (120) vs 91.5 (81) to 116 (101) and TEWL of 7.08 (2.03) to 9.97 (6.38) vs 7.65 (7.54) to 8.22 (6.52). Itch was reported by 14 (22.6%). Patients with itch had lower hydration and higher TEWL but were not significantly different from patients without itch. Conclusions: The vitiligous skin has reduced hydration and increased TEWL, suggesting a defective epidermal barrier. Thyroid antibody positivity was not associated with biophysical characteristics or itch. Itch was not associated with hydration, pH, and TEWL. An impaired epidermal barrier and itch need to be addressed in vitiligo management.