Skin Hydration and Facial Aging in Women Aged 30–60: An Observational Correlational Study Using Bioimpedance Analysis — Study Protocol

Background: Skin hydration is a central parameter in facial aging, yet it is rarely measured objectively in cosmetological practice. This protocol describes a pilot observational correlational study examining whether skin hydration levels, measured with the BT-Analyze bioimpedance device at seven facial zones, correlate with visual signs of aging rated by a blinded expert cosmetologist using a modified Glogau scoring system. Methods: A cross-sectional observational study will enroll 30 women divided into three age groups (30–40, 40–50, and 50–60 years). Skin hydration will be measured at seven standardized facial zones following 20-minute acclimation. An expert cosmetologist will rate aging from standardized photographs using a modified Glogau scale (0–18 points). Spearman rank correlation will be the primary statistical test. Expected outcomes: We expect lower BT-Analyze scores to correspond to higher Glogau aging scores. Findings will provide measurement-based support for hydration-focused skincare protocols in U.S. cosmetology practice. Trial registration: ClinicalTrials.gov, NCT07564869. Registered April 2026.