Body Mass Index z Scores Correlate with Epidermal Function in Chinese Children

BACKGROUND/OBJECTIVE: Epidermal function is altered in a number of cutaneous and extracutaneous disorders. To determine whether epidermal function is also altered in children with obesity, we assessed the correlation between the body mass index (BMI) z score and epidermal function in children. PARTICIPANTS AND METHODS: Participants were enrolled from outpatient clinic, schools and kindergartens. Epidermal biophysical properties, including transepidermal water loss rate, stratum corneum hydration and skin surface pH, were measured on the flexor forearm and shin. Correlations between epidermal biophysical properties and BMI were analyzed. In addition, the association of epidermal biophysical properties with BMI z score was also determined. RESULTS: Overall, BMI did not differ significantly between boys and girls among the age groups. BMI z scores correlated negatively with stratum corneum hydration levels and positively with skin surface pH in boys, but not in girls. The negative correlation between TEWL and BMI z score was not significant. Moreover, stratum corneum hydration levels were lower in boys with a BMI z score of ≥2 than in those with a BMI z score of −2 to 0.99. CONCLUSION: Both stratum corneum hydration levels and skin surface pH are significantly correlated with BMI z scores in boys, but not in girls. Whether epidermal function influences BMI or vice versa remains to be determined.