A review of water balance in ageing in health and disease.

The elderly are at increased risk of changes in body water and sodium, often accompanying comorbid disease states, which are associated with increased mortality. The clinical assessment of the hydration status of an elderly patient is difficult and the elderly care physician relies on both the clinical picture and laboratory investigation. Although still contentious, research suggests that the elderly may appreciate thirst less readily. However, healthy elderly may be able to produce an enhanced vasopressin response to osmotic stimulation compared to their younger counterparts, possibly in response to reduced renal function. The changes in these systems, when combined with coincident disease, place elderly patients at risk of water imbalance and electrolyte disturbance.