The ABCs of dehydration

Dehydration, although a concern at any age, holds alarming risks for people who are older. Affecting every part of the body, dehydration can have a huge impact on an older person’s day-to-day functioning, independence and life enjoyment, but the consequences can be much more serious. If an older person who is dehydrated then falls ill or has an accident, their body’s ability to recover is doubly compromised and the likelihood of hospitalisation and even death increases dramatically.

Even mild dehydration can cause tiredness, poor concentration, muscle weakness, memory problems and slower reaction times, all of which make daily life difficult as well as increase the risk of accidents and illness. It’s something to be taken seriously, yet it’s so easy to avoid.

In this article I’ll explain the risks of dehydration for older people, how to tell if it’s happening and what to do to prevent or reverse it.

Why is hydration so important?

The fluid in every organ and every cell of your body is essential for them to do what they need to do to keep you alive and well. This is why being dehydrated affects all your body systems.

Your body is about 60% water, with each of your organ systems requiring slightly different fluid levels. For example, smooth, efficient blood flow depends on fluid levels being higher than 80%, so if that level drops, your blood flow will be affected.

Skin is more than 60% water, and any reduction in that level—even from only mild dehydration—makes it much more vulnerable to damage and slower to repair itself. However, as you age, your skin is already becoming more fragile and more prone to frequent and severe damage than in your earlier years.

This means that becoming dehydrated when you’re older compounds the chances of skin injuries that are painful and can be slow to heal. Wounds often reduce your ability to get around and do the things you usually would (not to mention the expense of  their treatment, the increased need for support, and the pain). So making sure you avoid dehydration is essential for enjoying the life you hope for.

Dehydration affects the brain, too. Your brain just can’t fire on all cylinders when you are even a little dehydrated, no matter how old you are. This is partly because brain cells (‘neurons’), like all cells, need water to communicate with each other, and partly because dehydration also slows down blood flow, as I mentioned before.

Slowed blood flow affects fuel and nutrient delivery in the brain and reduces the efficiency of its clean-up systems, which are vital to keeping it working at peak. As you age, dehydration can lead to confusion and incoherence even more quickly, with increasing consequences.

Serious medical consequences of dehydration

• Heat injuries, including heat stroke

• Urinary and kidney problems, including urinary tract infections (UTIs)

• Psychosis or delirium (commonly from a combination of dehydration and an infection, such as a UTI)

• Seizures

• Low blood volume (hypovolemic) shock (the heart becomes unable to pump blood to the body)

• Death, if the dehydration is extreme

Hydration challenges for older people

Unfortunately, ageing itself can make dehydration more likely, and the symptoms and consequences of dehydration are sometimes dismissed as ‘part of being old’. That sort of ageist thinking means that the opportunity for reversing the dehydration and preventing its potentially disastrous consequences might be missed.

Making sure you get the fluids you need can be challenging as you grow older, because you don’t feel thirsty as soon as you should. Basically, this happens because the mechanisms that monitor hydration levels and prompt you to drink are affected by ageing and their messages don’t get through as well as they used to.

In fact, feeling thirsty becomes a far less useful indicator of dehydration as we move into our later years. Better signs include having a dry mouth or cracked lips, eyes feeling dry and/or ‘scratchy’, urine being a dark colour (it should ideally be the colour of dry grass or lighter), and pinched skin on the back of the hand not promptly going flat again.

The most common signs (or side effects) of dehydration

• Fatigue or lethargy

• Muscle weakness and cramps

• Cracked lips

• Headaches

• Dizziness

• Nausea

• Forgetfulness and confusion

• Deep rapid breathing or an increased heart rate or low blood pressure

• Sunken eyes

• Dryness or sticky mucus around and in the mouth

• Low urination

• Urinary tract infection (UTI)

Did you know?

Avoiding drinking is counterproductive

Many people in their later years avoid drinking, especially as evening approaches, aiming to reduce the need to get up during the night to have a wee. However, you might be surprised to learn that this can, in fact, have the opposite effect!

Drinking less than you need increases the concentration of the urine, which can irritate the bladder; this irritation generates signals to empty the bladder much more frequently. So you may find you need to get up more often instead of less often (even though not much comes out at each visit to the toilet)!

Eating and drinking intakes are linked

Feelings of thirst are often mixed up with feelings of hunger, so if your appetite for food declines you are likely to drink less, too. And because a lot of our daily water intake comes from the food we eat and the digestive process itself, eating less food for any reason decreases the amount of fluid available to your body and brain.

Fortunately, we do hold some fluid reserves in our bodies that can provide temporary backup. But these reserves are largely held in body muscle, so if you’ve lost weight (and therefore muscle (see article on Eating Well in Your 60s, 70s and Beyond) since your late 60s, you have also reduced that backup reserve, and you’ll need to be extra-vigilant.

Medications can affect hydration

A number of medications can contribute to dehydration. Most common are the diuretics, which are often called ‘fluid tablets’ and are designed to remove excess fluid from your body to relieve some of the symptoms of heart problems. Maintaining a balance between too much fluid affecting your heart and enough fluid to keep the rest of your body functioning is something that needs close monitoring by your doctor.

Be aware, too, that the dosage of diuretic a person requires can vary with weight loss and changes in their health, so don’t assume you always need the same dose. If you are unwell—especially with a fever—or heading for surgery, check the dosage with your doctor. Adjustments may need to be made until you have recovered so that you avoid the possibility of dehydration and delirium.

Other medications that can affect hydration levels include laxatives, ACE inhibitor blood pressure medications, steroids, some medications for type 2 diabetes and some antipsychotics. If you have any concerns about these, check with your pharmacist or doctor.

What to drink to prevent dehydration

You might have heard that most people should drink between 6 and 8 glasses or cups of liquid each day. What we actually need is about 30 to 35 millilitres of water for every kilogram of body weight, so you can work it out more accurately if you really want to!

Remember that it doesn’t all have to come from straight water; in fact, people with poor appetites need to drink fluids that also give some nutrition. Drinking a lot of water can make things worse for these people, because filling up on water means they may feel less like eating the food they need.

You can get your fluid intake from many different sources: all sorts of drinks—including tea, coffee, juices and milk drinks—and many different foods, such as fruits, soup, desserts, jelly, ice cream, casseroles. Pretty much anything that’s not dry will contribute some amount to your fluid intake.

A homemade rehydration drink recipe

If you have been acutely unwell with vomiting and/or diarrhoea, which both cause significant fluid losses, an oral rehydration drink can be a good idea. However, you don’t necessarily need to buy costly commercial products (which are more important for chronic or long-term gastrointestinal issues). This recipe, which can be flavoured if you wish, is cheap and easy to make:

• 6 teaspoons of sugar (don’t use artificial sweetener—the sugar is important)

• ½ a teaspoon of salt

• 1 litre (5 cups) of cooled boiled water

Stir the mixture until the salt and sugar dissolve. Take regular sips …Start with regular sips and increase the quantities you drink over a 24 hour period until you are urinating freely and the urine has returned to a pale colour.

Why risk triggering serious health problems and potentially decrease your enjoyment of life? It’s very easy to avoid being dehydrated and to set things right if your fluid levels have lowered. Make it a priority to look after yourself and ensure you’re taking in all the fluids your body needs to function well. And if you have any questions or concerns about dehydration, talk to your doctor straight away.

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Disclaimer: The information provided on this website is not a substitute for individual health advice from a doctor or dietitian.

by Ngaire Hobbins APD

Ngaire Hobbins is a fully qualified Australian dietitian and an expert on nutrition, ageing, brain health and dementia. She is passionate about supporting older adults to enjoy vital, independent lives through good nutrition. Visit Ngaire’s website to learn about her consultations, books, recipes, blog posts and speaker events. Some of the content in this article is an extract from Ngaire’s book Brain Body Food.