Gender differences in facial skin dielectric constant measured at 300 MHz

Background/purpose
Skin tissue dielectric constant (TDC) measurements at 300 MHz provide non-invasive data on free and bound tissue water. TDC-data is available for some body sites, but most is for female forearm. Contrastingly, there are no data on face-skin or comparative data between genders. Our goals were to obtain facial-TDC reference values and determine if TDC-values differ between genders.

Methods
TDC was measured at forehead, cheek, and forearm in 60 young adults (30 men) to a 1.5-mm depth. Measured TDC-values were compared with TDC-values calculated using skin-thickness data.

Results
Measured TDC-values ranged from 39.6 ± 2.9 at male-forehead to 28.2 ± 2.4 at female forearm and were significantly different (P < 0.001) among each site in the order forehead > cheek >forearm. Male TDC-values were greater than female TDC-values (P < 0.01) with differences from 5.6% at forehead to 11.3% at forearm. Calculated TDC-values incorporating site and gender skin-thickness differences yielded TDC-values at the most 3% different from measured values.

Conclusion
Gender differences should be considered in clinical studies in which men and women are included in a common study population with respect to experimental design and data interpretation. This is especially true if absolute TDC-values are of interest rather than changes in TDC-values on the same subject subsequent secondary to an intervention.