Effects of site and menstrual cycle on barrier function and stratum corneum water-holding capacity

Areas of the skin with similar anatomical structure may have different functional behaviour. In vivo barrier function and stratum corneum water-holding capacity during the menstrual cycle on two sites of the volar forearm (upper and lower) and on the anterior aspect of the thigh were evaluated using the plastic occlusion stress test (POST).

13 healthy women (age 31 ± 4) with regular menses entered the study. POST was performed by applying a plastic chamber (1.8 cm diameter) on the skin for 24 h. After removal the skin surface water loss (SSWL) was measured using an evaporimeter (EP1-Servomed, Sweden) every 5 min for 30 min. Measurements were taken on the 10th and 25th day of the menstrual cycle. Statistical analysis was performed using one-factor Anova for repeated measures. Free and bound water compartments of evaporation were also analysed.

Higher hydration and SSWL were detectable on the 25th day of the cycle. However, no significant influence of menstrual cycle was found. Significant differences between the upper and lower volar foream were detected (P < 0.001).

The differences observed were mainly related to the evaporation of bound water, confirming a different barrier function at the sites investigated; therefore, it must be taken into account that adjacent skin sites with equal structure may have different functional behaviour.