Assessment of extracellular dehydration using saliva osmolality
- 458 Downloads
When substantial solute losses accompany body water an isotonic hypovolemia (extracellular dehydration) results. The potential for using blood or urine to assess extracellular dehydration is generally poor, but saliva is not a simple ultra-filtrate of plasma and the autonomic regulation of salivary gland function suggests the possibility that saliva osmolality (Sosm) may afford detection of extracellular dehydration via the influence of volume-mediated factors.
This study aimed to evaluate the assessment of extracellular dehydration using Sosm. In addition, two common saliva collection methods and their effects on Sosm were compared.
Blood, urine, and saliva samples were collected in 24 healthy volunteers during paired euhydration and dehydration trials. Furosemide administration and 12 h fluid restriction were used to produce extracellular dehydration. Expectoration and salivette collection methods were compared in a separate group of eight euhydrated volunteers. All comparisons were made using paired t-tests. The diagnostic potential of body fluids was additionally evaluated.
Dehydration (3.1 ± 0.5 % loss of body mass) decreased PV (−0.49 ± 0.12 L; −15.12 ± 3.94 % change), but Sosm changes were marginal (<10 mmol/kg) and weakly correlated with changes in absolute or relative PV losses. Overall diagnostic accuracy was poor (AUC = 0.77–0.78) for all body fluids evaluated. Strong agreement was observed between Sosm methods (Expectoration: 61 ± 10 mmol/kg, Salivette: 61 ± 8 mmol/kg, p > 0.05).
Extracelluar dehydration was not detectable using plasma, urine, or saliva measures. Salivette and expectoration sampling methods produced similar, consistent results for Sosm, suggesting no methodological influence on Sosm.
KeywordsHypohydration Hypovolemia Volume depletion Hydration assessment Furosemide
- Adolph EF, Wills JH (1947) Thirst. In: Visscher MB, Bronk DW, Landis EM, Ivy AC (eds) Physiology of Man in the Desert, Interscience, New York, NY, pp 241–253Google Scholar
- Caddy B (1984) Saliva as a specimen for drug analysis. In: Baselt RC (ed) Advances in analytical toxicology. Biomedical Publications, Foster City, pp 198–254Google Scholar
- Freund BJ, Young AJ (1996) Environmental influences body fluid balance during exercise: cold exposure. In: Buskirk ER, Puhl SM (eds) Body Fluid Balance: Exercise and Sport. CRC, New York, pp 159–181Google Scholar
- Hagan RD, Diaz FJ, McMurray RG, Horvath SM (1980) Plasma volume changes related to posture and exercise. Proceedings of the Society for Experimental Biology and Medicine 165:155–160Google Scholar
- Hoyt RW, Honig A (1996) Body fluid and energy metabolism at high altitude. In: Blatteis CM, Fregley MJ (eds) Handbook of Physiology: Adaptation to the environment, Oxford University Press for the American Physiological Society, New York, pp 1277–1289Google Scholar
- Institute of Medicine (2005) Dietary reference intakes for water, potassium, sodium, chloride, and sulfate. Dietary reference intakes for water, potassium, sodium, chloride, and sulfate The National Academies Press, Washington, DCGoogle Scholar
- Jackson A, Pollock M (1985) Practical assessment of body composition. Physician Sports Med J 13:75–90Google Scholar
- McGee S, Abernethy III WB, Simel DL (1999) The rational clinical examination. Is this patient hypovolemic? J Amer Med Assoc 281:1022–1029Google Scholar
- Peacock WF, Soto KM (2010) Current techniques of fluid status assessment. Contrib Nephrol 164:128–142Google Scholar
- Seay JF, Ely BR, Kenefick RW, Sauer SG, Cheuvront SN (2013) Hypohydration does not alter standing balance. Mot Control 17:190–202Google Scholar
- World Health Organization (1995) The treatment of diarrhoea: a manual for physicians and other senior health workers. Department of Child and Adolescent Health and Development, Geneva, SwitzerlandGoogle Scholar