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Dehydration
Dehydration – The Causes
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If you're an average adult, every day you lose close to 2.5
litres of water simply by sweating, breathing and
eliminating waste. You also lose electrolytes — minerals
such as sodium, potassium and calcium that maintain the
balance of fluids in your body. And all this is before you
even think about mowing the lawn on a sticky afternoon,
working out at the gym or rearranging the living room
furniture.
Even when you're active, you normally can replenish what
you've lost through the food and liquids you consume, but
sometimes you eliminate more water and salts than you
replace. The result is dehydration — your system literally
dries out. Because water makes up about 60 percent of your
body weight, this can cause physiological changes that may
affect your health, even if you don't have noticeable signs
or symptoms.
Just a small reduction in body fluids and electrolytes, for
instance, leads to a lower circulating blood volume. As a
result, your heart has to pump harder to maintain adequate
blood flow to your vital organs, and your body is less able
to control blood pressure, distribute nutrients and
eliminate waste.
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What's more, because blood flow to your skin is reduced and
you have less water in your system, you don't perspire or
dissipate heat the way you normally would. In extreme cases,
this can cause your body core temperature to soar, leading
to heat exhaustion and possibly heat stroke — a potentially
life-threatening condition in which your body temperature
climbs to 104 F or more, sometimes reaching as high as 107
F.
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Not all cases of dehydration have such serious consequences,
but even a 2 percent loss of body weight can affect athletic
performance, and a 3 percent to 5 percent loss adversely
affects reaction time, concentration and judgment. What's
more, dehydration is insidious; these effects often occur
before you're aware of them.
How dehydration happens
Sometimes dehydration occurs for simple reasons: You don't
drink enough because you're sick, busy or just not thirsty,
or because you lack access to potable water when you're
travelling, hiking or camping.
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Other causes of dehydration include:
Exercise
Everyday, athletes of all ages and skill levels – pint-sized
football players, treadmill joggers, professional cyclists
and tennis players – experience some degree of dehydration.
The reason is simple: you lose water when you sweat more in
the hot weather, you can also become dehydrated in winter,
especially if you wear layers of insulated clothing or work
out in an overheated gym. Humidity compounds the problem
because it increases sweating and inhibits cooling.
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Although no one who is active is immune, preteens and
teens who participate in sports are especially
susceptible, both because of their smaller body weight
and because they may not be experienced enough to know
the warning signs of dehydration.
Young athletes are also at risk if they don’t become
acclimated to heat and humidity before a workout or if
they exercise too strenuously in an effort to make the
team. |
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Fever
In general, the higher your fever, the more dehydrated you
become. If you have a fever in addition to diarrhoea and
vomiting, you lose even more fluids.
Increased urination
This is most often the result of undiagnosed or uncontrolled
diabetes, a disease that affects the way your body uses
blood sugar and that often causes increased thirst and more
frequent urination. Another condition, diabetes insipidus,
is also characterised by excessive thirst and urination, but
in this case the cause is a hormonal disorder that makes
your kidneys unable to conserve water. Certain medications –
diuretics drugs – as well as alcohol can also lead to
dehydration, generally because they cause you to urinate or
perspire more than normal.
Long airplane flights
The air in the cabins of most commercial airplanes is drier
than the Sahara Desert, with humidity levels hovering around
10 percent or less. Compounding the problem for some people
is alcohol – a readily available in-flight beverage. The
longer the flight and the more alcohol you drink, the more
dehydrated you become – it takes 8 ounces of water to make
up for every 1.5 ounces of alcohol you consume. Older adults
and people who have diabetes or who takes drugs that
increase urination are particularly at risk.
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The best advice
when flying is to bypass the alcohol cart and drink bottled
water instead. Sugary drinks, coffee and tea aren’t ideal
substitutes. Although new research suggests that
caffeine-containing beverages aren’t as dehydrating as once
thought, water is still your best bet. And don’t worry about
having to climb over your seatmates to get to the bathroom –
preventing dehydration is worth a little social
embarrassment. In addition to all the other problems it can
cause, a lack of fluids combined with arid airplane air
dries out your nasal passages, increasing your risk of upper
respiratory infections. |
Hot, sunny climates
It makes sense that you perspire more – and therefore lose
more fluids – in hot climates. High humidity makes matters
worse because it prevents sweat from evaporating quickly.
Burns
Doctors classify burns according to the depth of the injury
and the extent of tissue damage Third-degree burns are the
most severe, penetrating all three layers of skins, and
often destroying sweat glands, haro follicles and nerve
endings. People with third-degree burns or extensive first
or second-degree burns experience profound fluid loss, and
the resulting dehydration can be life threatening.
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