A cross-sectional study of variations in the biophysical parameters of skin among healthy volunteers

Background: Biophysical parameters of skin such as trans-epidermal water loss (TEWL), hydration, elasticity, pH, and sebum reflects it functional integrity. Advances in technology have made it possible to measure these parameters by non-invasive methods. These parameters are useful for the prediction of disease and its prognosis. It also helps in developing new skin care products according to various skin types, and to evaluate, modify, or compare the effects of existing products. Aim: The aim of the study was to measure, evaluate, and analyze variations in biophysical parameters at pre-selected skin sites in healthy Indian volunteers, across different age groups and gender. Methods: The study was conducted among 500 healthy Indian volunteers, between 5 and 70 years of age, in the outpatient department of dermatology at Sir T. Hospital, Bhavnagar. Biophysical parameters such as TEWL, hydration, elasticity, and sebum content was measured on four pre-selected body sites by a Dermalab instrument (Cortex Technology, Denmark). The skin pH was measured with a sensitive pH probe (BEPL 2100). Results: All parameters were higher in males compared to females, except for sebum content, which was equal in both genders. Transepidermal water loss and hydration was lower in middle and older age groups. The skin pH showed no statistically significant difference with age. Sebum content was higher in middle and older age groups. The nose had the highest sebum content across all age groups. The forehead showed higher median values of TEWL and hydration compared to other sites. Though elasticity has highest value on forearm, only leg region showed statistically significant value. Limitations: The present study was confined to a single geographical area, so the effect of environment changes could not be judged accurately. Seasonal variations were not studied as it was a cross-sectional study. Conclusion: Skin properties vary with age, gender, and location on the body. This knowledge will help to create a database of these parameters in the Indian population. It would assist in the diagnosis of various clinical conditions and monitor therapeutic response.