Chen C.-HLu Y.-PLee A.-TTung C.-WTsai Y.-HTsay H.-PLin C.-TYang J.-T.CHIH-TING LIN2022-04-252022-04-25202120754426https://www.scopus.com/inward/record.uri?eid=2-s2.0-85109114555&doi=10.3390%2fjpm11060577&partnerID=40&md5=99468a6e8bd1c452277784a0915bd2dahttps://scholars.lib.ntu.edu.tw/handle/123456789/607020The evaluation of fluid status can save adults from life-threatening conditions, but the current methods are invasive or time-consuming. Therefore, we developed a portable device for measuring salivary conductivity. This prospective observational study enrolled 20 volunteers with no history of systemic diseases. Participants were observed for 13 h, including water restriction for 12 h followed by rehydration with 1000 mL water within 1 h. Serum and urine biomarkers for fluid status, thirst scales, and salivary conductivity were collected during dehydration and rehydration. No significant differences in age, body mass index, glycohemoglobin, and estimated glomerular filtration rate were noted between sexes. Salivary conductivity increased after water restriction and decreased after rehydration. Similarly, urine osmolality, urine specific gravity, thirst intensity scales, and body weight followed the same trend and were statistically significant. The angiotensin-converting enzyme and aldosterone levels showed the same trend, without reaching statistical significance. The red blood cell count and hemoglobin concentration also followed the same trend. Analyzing the receiver operating characteristic curves, the area under the curve was 0.707 (95% confidence interval 0.542–0.873, p = 0.025). Using the Youden index, the optimal cutoff determined as 2678.09 ?s/cm (sensitivity: 90%, specificity: 55%). This biodevice effectively screened dehydration among healthy adults. ? 2021 by the authors. Licensee MDPI, Basel, Switzerland.Fluid statusPortable biodeviceSalivary conductivityaldosteronebiochemical markercopeptincreatininedipeptidyl carboxypeptidasehemoglobinadultaldosterone blood levelarea under the curveArticlebiochemical analysisblood analysisblood cell countblood samplingbody compositionbody fluidbody fluid compartmentbody weightcontrolled studycreatinine blood levelcreatinine urine leveldehydrationdiagnostic test accuracy studyenzyme blood levelerythrocyte countestimated glomerular filtration ratefemalefluid balanceglucose blood levelhematocrithemoglobin blood levelhumanhuman experimentlongitudinal studymalemedical parametersnormal humanobservational studyreceiver operating characteristicrehydrationsaliva analysissalivary conductivitysensitivity and specificitysodium blood levelsodium urine levelthirst intensityurinalysisurinary excretion fractionurine osmolalityurine specific gravitywater deprivation[SDGs]SDG3[SDGs]SDG6journal article10.3390/jpm110605772-s2.0-85109114555