MC Faes, MD, MSc, Department of Geriatric Medicine, University Medical Centre Nijmegen, The Netherlands.
MG Spigt, PhD, Department of General Practice/Research Institute CAPHRI, University of Maastricht, The Netherlands.
MGM Olde Rikkert MD, PhD, Department of Geriatric Medicine, University Medical Centre Nijmegen, The Netherlands.

Homeostasis of fluid balance is an important prerequisite for healthy aging. The high prevalence of disturbances of fluid balance among older adult patients has triggered clinical research on age- and disease-related changes in water homeostasis. Empirical findings on risk factors of dehydration and on diagnostic and therapeutic strategies are reviewed in this paper. No single measure has proved to be the gold standard in the diagnosis of dehydration. Diagnosing dehydration and monitoring fluid balance requires repeated measurements of weight, creatinine, and physical signs such as tongue hydration. Rehydration and prevention requires fluid on prescription (> 1.5 litre/day), and the route of fluid administration depends on the acuteness and severity of clinical signs.
Keywords: older adults, dehydration, fluid therapy, risk factors, diagnosis.