Comparative study of five instruments measuring stratum corneum hydration (Corneometer CM 820 and CM 825, Skicon 200, Nova DPM 9003, DermaLab). Part II. In vivo

Background/Aims: The hydration state of stratum corneum can be measured with different instruments. In the present study, five instruments were compared under different experimental in vivo conditions: Corneometer CM 820 and CM 825 (both capacitance based), Skicon 200 (conductance), Nova DPM (impedance based capacitance) and DermaLab (capacitance). Methods: Seven anatomical sites were tested, a sorption-desorption test (SDT) and a moisture accumulation test (MAT) were performed. Different hydration states were created on the volar forearms by occluded application of an oil-in-water (o/w) emulsion, glycerol and urea containing oil-in-water (o/w) emulsion, an untreated control site and a site after lipid extraction with acetone. Measurements were performed 15 min after removal of occlusion. Results: The coefficient of variation for CM 820 ranged between 9.3% and 23.7%; for CM 825 between 14.9% and 36.8%; for Skicon 200 between 53.0% and 167.3%; for Nova DPM between 36.4% and 95.8%; for DermaLab between 23.6% and 45.6%. All devices showed a highly significant correlation (P <0.0001) with a high Spearman coefficient r ranging between 0.7928 and 0.9358. Conclusions: CM 820 and CM 825 seem to differentiate more precisely than Nova DPM, Skicon 200 and DermaLab in dry conditions according to previous findings, i.e., that conductance measurements might be more sensitive for hydrated skin and capacitance measurements might be more sensitive for dry skin conditions. The CM 825, the Skicon 200 and the Nova DPM are suitable for dynamic measurements of hydration parameters of the stratum corneum.