Development and evaluation of a rapid skin taurine measurement device using skin blotting for the early detection of dehydration

Abstract

Aim

Skin blotting is a noninvasive method to collect molecules like skin taurine, a dehydration indicator, by applying a membrane to the skin. However, quantifying skin taurine takes an hour due to the long process of staining and measurement. This study aimed to determine optimal staining conditions and assess the reliability and validity of spraying and light transmittance as new methods for skin blotting. Image analysis was used to evaluate the impact of these methods.

Methods

This study consisted of two parts. Study 1 focused on determining taurine staining conditions on the anion exchange membrane. Ethanol concentration for dissolving ninhydrin and spray time were optimized using a standard sample. Light transmittance and image analysis were used to quantify taurine. The relationship between taurine concentration and light transmittance or brightness (from image analysis) was evaluated. Study 2 confirmed the reliability and validity of the new methods using human samples. Reliability was assessed using the intraclass correlation coefficient (ICC), and validity was determined by correlation coefficients between taurine levels quantified by the conventional method with those quantified by light transmittance or image analysis.

Results

The optimal spray time and ethanol concentration were 0.5 s and 90%, respectively, reducing measurement time to 7 min (light transmittance) and 10 min (image analysis). The ICC was 0.48 for light transmittance and 0.81 for image analysis. The correlation coefficients were r = 0.530 for light transmittance and r = 0.609 for image analysis.

Conclusions

Image analysis, which measures a wider area, showed better reliability and validity in quantifying skin taurine.