The ageing process increases the risk of fluid and electrolyte imbalance.

Water is the largest single component of the body, making up between 45 and 75 per cent of the total body mass. A decrease in body fluid volume typically stimulates thirst which usually leads to increased fluid intake. However, large numbers of patients in A&E departments have a primary diagnosis of fluid and electrolyte imbalance or volume depletion. In the case of older people, this group has a diminished thirst response and decreased renal function making them at greater risk of developing dehydration.