Hydration in older people
How much fluid we should have everyday is very confusing. Everything from 500 ml to 3 L is recommended. However, there are some ageing changes that do impact on a safe and effective fluid intake for older people.
Yes; it is very important that older people do not become dehydrated. When I was working as a nurse in an Acute Aged Care Ward at a large Sydney hospital, many older people were admitted both for and with dehydration.
There are several reasons why an older person can become dehydrated quickly especially in hot weather.
There is a reduced thirst drive. Most older people can be dehydrated and be unaware and the first Signs & Symptoms (S&S) can be fatigue, light headiness, dizziness when standing up, slight confusion that may progress, increased heart and breathing rates, sore muscles and joints. Fluid is need for the efficient running of your body’s functions.
Urine output and colour of the urine is not a good indicator of hydration in an older person. The changes in the kidney function and the corresponding fluid regulating hormones, does not preserve fluid in an older person, even when dehydrated.
The older person’s kidneys also do not maintain electrolyte balance efficiently (calcium, potassium, sodium, phosphorus, magnesium).
There is reduced storage of fluid in an older person’s muscle mass, because, in older people the muscle mass is reduced. Younger people have a good storage of fluid in their muscles.
Skin turgor of the elasticity response of the skin is used in younger people to test for dehydration but in older people, the loss of collagen and elastin in the skin makes this test null.
Any episode of diarrhoea &/or vomiting can quickly result in a substantial loss of fluid and electrolytes that can not easily be replaced. Any fluid loss in an older person needs to have action taken. At home this may mean increased fluid intake with electrolytes ( eg. Hydralyte) for a period of time and observe for any S&S of dehydration and electrolyte loss.
Increased water on its own may make the loss of electrolytes worse as any remaining electrolytes may be flushed out if large volumes of just water are given.
So prevention is the key. I suggest (see research articles) a 1 L water bottle filled at the beginning of the day and sipped through the next 12 – 15 hours. Add mint leaves or lime/lemon juice if you don’t like the plain water. Take care with too much coffee or tea. Water is best.
It is a myth that not drinking fluid after 4pm reduces urine output overnight. The urine is still produced all the time in older people due to changes in the circadian rhythm of diuretic hormones. Changes in the bladder wall’s protective mucous membranes, means this urine is sitting in the bladder, irritating the bladder wall lining, often causing urgency to urinate. Urgency to urinate is a common reason for falls overnight.
This is general information. If you are on fluid restrictions for a medical condition or diuretic medications, talk with your medical officer about your recommended amount of daily fluid intake.
further reading
Li, S., Xiao, X. & Zhang, X. 2023. Hydration Status in Older Adults: Current Knowledge and Future Challenges. Nutrients. 1
