Point-of-Care Saliva Osmolarity Testing for the Screening of Hydration in Older Adults With Hypertension

Published:September 26, 2022DOI:



      Older adults have an elevated risk of dehydration, a state with proven detrimental cognitive and physical effects. Furthermore, the use of diuretics by hypertensive patients further compounds this risk. This prospective study investigated the diagnostic accuracy of point-of-care (POC) salivary osmolarity (SOSM) measurement for the detection of dehydration in hypertensive adults with and without diuretic pharmacotherapy.


      Prospective diagnostic accuracy study.


      Home visits to patients recruited from 4 community health centers in West Sulawesi, Indonesia.


      A total of 148 hypertensive older adults (57 men, 91 women). The mean ages of male and female patients were 69.4 ± 11.4 and 68.1 ± 7.8 years, respectively.


      Hypertensive adults were divided into 2 groups based on the presence of diuretics in their pharmacotherapeutic regimen. First-morning mid-stream urine samples were used to perform urine specific gravity (USG) testing. Same-day SOSM measurements were obtained using a POC saliva testing system.


      Both USG (P = .0002) and SOSM (P < .0001) were significantly elevated in hypertensive patients with diuretic pharmacotherapy. At a USG threshold of ≥1.030, 86% of diuretic users were classified as dehydrated compared with 55% of non-using participants. A strong correlation was observed between USG and SOSM measurements (r = 0.78, P < .0001). Using a USG threshold of ≥1.030 as a hydration classifier, an SOSM threshold of ≥93 mOsm had a sensitivity of 78.6% and a specificity of 91.1% for detecting dehydration.

      Conclusions and Implications

      Hypertensive patients on diuretics have significantly higher first-morning USG and SOSM values, indicating a higher likelihood of dehydration relative to those on other classes of antihypertensive medication. POC SOSM assessment correlates strongly with first-morning USG assessment, and represents a rapid and noninvasive alternative to urinary hydration assessment that may be applicable for routine use in populations with elevated risk of dehydration.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Journal of the American Medical Directors Association
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Stookey J.D.
        High prevalence of plasma hypertonicity among community-dwelling older adults: results from NHANES III.
        J Am Diet Assoc. 2005; 105: 1231-1239
        • Sfera A.
        • Cummings M.
        • Osorio C.
        Dehydration and cognition in geriatrics: a hydromolecular hypothesis.
        Front Mol Biosci. 2016; 3: 18
        • Hamrick I.
        • Norton D.
        • Birstler J.
        • et al.
        Association between dehydration and falls.
        Mayo Clin Proc Innov Qual Outcomes. 2020; 4: 259-265
        • Mentes J.C.
        • DeVost M.A.
        • Nandy K.
        Salivary osmolality, function, and hydration habits in community-dwelling older adults.
        SAGE Open Nurs. 2019; 52377960819826253
        • Riebl S.K.
        • Davy B.M.
        The hydration equation: update on water balance and cognitive performance.
        ACSMs Health Fit J. 2013; 17: 21-28
        • Mentes J.
        • Aronow H.
        Comparing older adults presenting with dehydration as a primary diagnosis versus a secondary diagnosis in the emergency department.
        J Aging Res Clin Pract. 2016; 5: 181-186
        • Hooper L.
        • Bunn D.K.
        • Downing A.
        • et al.
        Which frail older people are dehydrated? The UK DRIE study.
        J Gerontol A Bio Sci Med Sci. 2016; 71: 1341-1347
        • Koch C.A.
        • Fulop T.
        Clinical aspects of changes in water and sodium homeostasis in the elderly.
        Rev Endocr Metab Disord. 2017; 18: 49-66
        • Mentes J.
        Oral hydration in older adults: greater awareness is needed in preventing, recognizing, and treating dehydration.
        AJN Am J Nurs. 2006; 106: 40-49
        • Sarafidis P.A.
        • Georgianos P.I.
        • Lasaridis A.N.
        Diuretics in clinical practice. Part I: mechanisms of action, pharmacological effects and clinical indications of diuretic compounds.
        Expert Opin Drug Saf. 2010; 9: 243-257
        • Jarari N.
        • Rao N.
        • Peela J.R.
        • et al.
        A review on prescribing patterns of antihypertensive drugs.
        Clin Hypertens. 2015; 22: 1-8
        • Puga A.
        • Partearroyo T.
        • Varela-Moreiras G.
        Hydration status, drug interactions, and determinants in a Spanish elderly population: a pilot study.
        J Physiol Biochem. 2018; 74: 139-151
        • Lancaster K.J.
        • Smiciklas-Wright H.
        • Heller D.A.
        • et al.
        Dehydration in black and white older adults using diuretics.
        Ann Epidemiol. 2003; 13: 525-529
        • Kalisch Ellett L.
        • Pratt N.
        • Le Blanc V.
        • et al.
        Increased risk of hospital admission for dehydration or heat-related illness after initiation of medicines: a sequence symmetry analysis.
        J Clin Pharm Ther. 2016; 41: 503-507
        • Fortes M.B.
        • Owen J.A.
        • Raymond-Barker P.
        • et al.
        Is this elderly patient dehydrated? Diagnostic accuracy of hydration assessment using physical signs, urine, and saliva markers.
        J Am Med Dir Assoc. 2015; 16: 221-228
        • Bunn D.K.
        • Hooper L.
        Signs and symptoms of low-intake dehydration do not work in older care home residents-DRIE Diagnostic Accuracy Study.
        J Am Med Dir Assoc. 2019; 20: 963-970
        • Cheuvront S.N.
        Urinalysis for hydration assessment: an age-old problem.
        Am J Clin Nutr. 2016; 104: 3-4
        • Hooper L.
        • Bunn D.K.
        • Abdelhamid A.
        • et al.
        Water-loss (intracellular) dehydration assessed using urinary tests: how well do they work? Diagnostic accuracy in older people.
        Am J Clin Nutr. 2016; 104: 121-131
        • Walsh N.P.
        • Laing S.J.
        • Oliver S.J.
        • et al.
        Saliva parameters as potential indices of hydration status during acute dehydration.
        Med Sci Sports Exerc. 2004; 36: 1535-1542
        • Muñoz C.
        • Johnson E.
        • Demartini J.
        • et al.
        Assessment of hydration biomarkers including salivary osmolality during passive and active dehydration.
        Eur J Clin Nutr. 2013; 67: 1257-1263
        • Pranavmurthi V.
        • Webb C.
        • Hutzley V.
        • et al.
        Independent validation of a commercial saliva osmometer for hydration monitoring.
        Military Health System Research Symposium, August 24-27, 2020
        • Faidah N.
        • Soraya G.V.
        • Erlichster M.
        • et al.
        Detection of voluntary dehydration in paediatric populations using non-invasive point-of-care saliva and urine testing.
        J Paediatr Child Health. 2021; 57: 813-818
        • Rodriguez G.J.
        • Cordina S.M.
        • Vazquez G.
        • et al.
        The hydration influence on the risk of stroke (THIRST) study.
        Neurocrit Care. 2009; 10: 187-194
        • Cheuvront S.N.
        • Ely B.R.
        • Kenefick R.W.
        • et al.
        Biological variation and diagnostic accuracy of dehydration assessment markers.
        Am J Clin Nutr. 2010; 92: 565-573
        • Hew-Butler T.D.
        • Eskin C.
        • Bickham J.
        • et al.
        Dehydration is how you define it: comparison of 318 blood and urine athlete spot checks.
        BMJ Open Sport Exerc Med. 2018; 4: e000297
        • Rowat A.
        • Smith L.
        • Graham C.
        • et al.
        A pilot study to assess if urine specific gravity and urine colour charts are useful indicators of dehydration in acute stroke patients.
        J Adv Nurs. 2011; 67: 1976-1983
        • Ekpenyong C.E.
        • Akpan I.-A.M.
        High prevalence and associated risk factors of dehydration among college students: implications for health and academic performance.
        Inter J Comm Med Pub Health. 2017; 4: 1043-1055
        • Montazer S.
        • Farshad A.A.
        • Monazzam M.R.
        • et al.
        Assessment of construction workers’ hydration status using urine specific gravity.
        Int J Occup Med Environ Health. 2013; 26: 762-769
        • Brake D.
        • Bates G.
        Fluid losses and hydration status of industrial workers under thermal stress working extended shifts.
        Occup Environ Med. 2003; 60: 90-96
        • Cheuvront S.N.
        • Munoz C.X.
        • Kenefick R.W.
        The void in using urine concentration to assess population fluid intake adequacy or hydration status.
        Am J Clin Nutr. 2016; 104: 553-556
        • Chadha V.
        • Garg U.
        • Alon U.S.
        Measurement of urinary concentration: a critical appraisal of methodologies.
        Pediatr Nephrol. 2001; 16: 374-382
        • Cheuvront S.N.
        • Kenefick R.W.
        • Zambraski E.J.
        Spot urine concentrations should not be used for hydration assessment: a methodology review.
        Int J Sport Nutr Exerc Metab. 2015; 25: 293-297
        • Rutherfurd-Markwick K.
        • Starck C.
        • Dulsen D.
        • et al.
        Comparison of three salivary collection methods to assess physiological markers.
        J Food Nutr Metabol. 2020; : 1-9