Dehydration occurs when the body loses more water than is taken in. It is often accompanied by disturbances in the body’s mineral salt or electrolyte balance – especially disturbances in the concentrations of sodium and potassium.
How is dehydration caused?
Mild dehydration is common and usually
caused by not drinking enough fluids throughout the day. In children,
diarrhoea is a common cause.
Fluids are continuously lost through
normal body functions such as sweating, breathing and urinating. Common
causes of dehydration include gastrointestinal water loss caused by
diarrhoea and vomiting, excessive urination, excessive water loss
through the skin (sweating) and lungs (breathing) due to heat and/or
humidity, physical activity and fever or burns.
Diarrhoea
One of the most
common reasons a person loses excess water is an infection that causes
diarrhoea. Diarrhoea may be caused by bacteria, viruses or parasites. A
significant amount of water can be lost with each bowel movement – up to
1 litre per hour in extreme cases. Worldwide, more than four million
children die each year because of dehydration from diarrhoea.
Vomiting
The rapid loss of
water that occurs with severe and sustained vomiting makes dehydration
more likely to occur, as it is difficult to restore hydration status by
drinking. The risk of dehydration due to vomiting is higher in infants
and children, in the elderly, in people with eating disorders (e.g.
bulimia) and anyone taking medications that can cause vomiting.
Excessive urination
There are certain
medications that increase urination beyond normal levels (e.g.
diuretics), and there are conditions that affect kidney function,
leading to the loss of body water through urine. Conditions that may
affect urine production include diabetes and kidney cancer. Diabetes is
characterised by elevated blood sugar levels causing sugar to spill into
the urine and excessive urination which can lead to significant
dehydration.
Sweating
Sweating or
perspiration is the mechanism used by the body to cool itself in
conditions of heat, humidity and physical activity. Humidity can play a
greater role in dehydration than heat, because the sweat drips from the
body rather than evaporating, and thus does not cause a loss of heat
from the body. However, high rates of sweating can also occur during
sports or other vigorous physical activity in cool and dry conditions,
contributing to the risk of dehydration. Heavy clothing limits sweat
evaporation meaning that body heat is not dissipated causing the body to
lose even more water as it attempts to lose more heat.
Fever or burns
These conditions,
including sunburn, increase body temperature, requiring more fluid for
proper body functioning. Fever is present due to an infection and the
body uses a significant amount of water in the form of sweat to cool
itself. Burn victims become dehydrated because water seeps into the
damaged skin and is lost by evaporation.
Consequences
Mild dehydration can cause symptoms such as thirst, headache, weakness,
dizziness and fatigue and generally makes people feel tired and
lethargic. Symptoms of moderate dehydration may include dry mouth,
little or no urine, sluggishness, a rapid heartbeat and lack of skin
elasticity. Severe dehydration is a life-threatening medical emergency,
and is characterized by extreme thirst, no urine, rapid breathing,
altered mental state and cold, clammy skin.
Chronic dehydration can increase the risk of infection, particularly of
the urinary tract. The kidneys and other major organs that receive a
decreased blood flow may begin to fail. Kidney failure is a common
occurrence, although it is reversible if it is due to dehydration and is
treated early. Decreased blood supply to the brain may cause confusion,
impairing both cognitive function and coordination.
No comments:
Post a Comment