Dileep Lobo is Professor of Gastrointestinal Surgery at the University of Nottingham and Consultant Hepatopancreaticobiliary Surgeon at Queen’s Medical Centre. In this blog, he discusses his recent Age & Ageing paper on hydration.
Older adults are susceptible to dehydration because of changes that occur with age such as an increase in the threshold at which they become thirsty, which means that they may be in a greater state of dehydration before fluid is consumed.
Other changes associated with ageing such as a reduced kidney function can limit the ability to conserve water & increase susceptibility to dehydration. Acute illness is also a significant risk factor as it often results in significant physiological stress and can results in organ dysfunction, therefore, increasing the susceptibility of older adults to dehydration.
This pilot study conducted at the University of Nottingham was funded by the European Hydration Institute and aimed to assess the prevalence of hyperosmolar dehydration (HD) (dehydration associated with greater water than salt loss) and how it influenced the outcome in hospitalised older adults aged > 65 years. Hydration status was measured using serum osmolality which measures the concentration of salts to water ratio of the blood. Two-hundred patients were recruited to the study with over a third found to have HD at admission.
However, only 12% of the patients had a clinical diagnosis of dehydration. Moreover, almost two-thirds of those that were dehydrated at admission were also dehydrated 48 hours later. The study also reported that patients with HD at admission had higher in-hospital death rate. The findings of the study highlight the difficulty in recognising dehydration in older adults due the age related changes that mean that clinical signs normally associated with dehydration are not specific to the condition and can be attributed to other causes. In addition, the lack of widely accepted hydration assessment tool is likely to exacerbate the situation. As a result, dehydration may be picked up late and may, therefore, result in increased risk of complication such as kidney injury. However, it is important to note that there is limited evidence supporting the use of serum osmolality as a measure of hydration in the clinical setting, although it is widely used in human physiology studies to assess hydration status. Moreover, it is important to note that this study reports an association between dehydration and mortality, however, it is difficult to know whether dehydration caused the mortality or whether it is a manifestation of severe illness. Further work is therefore required to develop hydration assessment tools and to help clarify these relationships. Comprehensive guidelines are also required to help implement and monitor a real change in the way hydration is assessed and managed in older adults.