Salivary molecules as indicators of hydration status

Introduction: Maintaining an appropriate level of hydration is essential to health, especially when doing physical exercise. Thus, the importance of monitoring the before, during and after exercise status. Therefore, knowing and studying the changes and indicators that may provide reliable information on fluctuations in a simple, quick manner, via non-invasive sampling techniques becomes essential. Material and Methods: The data analyzed and processed (α-amylase, K+, Cl-, cortisol, total protein, and osmolality concentration in saliva) in this study are available on the free access research platform for complex physiological signals (https://physionet.org/content/qde/1.0.0/). Ten male subjects voluntarily took part in this study. The median and standard deviation of height, body weight, and age were 179 ±7.5 cm. 79.3 ±9.0 kg. and 25.5 ±3.7 years, respectively. Results: The α-amylase, K+, cortisol, total protein, and osmolality concentration in saliva showed significant variations for moderate dehydration levels. For the cases of Cl- concentration changes in saliva, statistically significant changes can be observed at a much earlier stage (in mild dehydration conditions). Conclusions: The results suggest that Cl- concentration in saliva might be used as an indicator for the hydration status. Therefore, a scale to monitor the hydration status is proposed.