Electrical impedance measurements at different skin sites related to seasonal variations

BACKGROUND/AIMS: In a previous study we mapped differences in electrical impedance between different anatomical locations related to age and sex. Now we employ the electrical impedance technique for studying the seasonal variations for the same skin sites. METHOD: The investigation was performed on 48 healthy volunteers divided into two groups on the basis of sex. Readings of electrical impedance were taken from ten different body locations at each of the four seasons during one year. Electrical impedance spectra were measured in the frequency range 1 kHz to 1 MHz, and four impedance indices based on the complex impedance values at 20 kHz and 500 kHz were calculated. RESULTS: The baseline values varied from one site to another and increased significantly for most sites from the winter to the summer, while the changes from October to March were negligible. Using ANOVA, the seasonal variation was found to be a more important factor than sex. CONCLUSIONS: Our results suggest that seasonal variations for different skin sites should be taken into consideration when using the electrical impedance technique.