What Is Dehydration? What Causes Dehydration?

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Main Category: Sports Medicine / Fitness
Also Included In: Public Health;  Pediatrics / Children's Health;  Seniors / Aging
Article Date: 10 Jun 2009 - 8:00 PST

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Dehydration (from the Greek hydor (water)) and the Latin prefix de- (indicating deprivation, removal, and separation) occurs when more water and fluids are exiting the body than are entering the body. With about 75% of the body made up of water found inside cells, within blood vessels, and between cells, survival requires a rather sophisticated water management system. Luckily, our bodies have such a system, and our thirst mechanism tells us when we need to increase fluid intake. Although water is lost constantly throughout the day as we breathe, sweat, urinate, and defecate, we can replenish the water in our body by drinking fluids. The body can also shift water around to areas where it is more needed if dehydration begins to occur.

Most occurrences of dehydration can be easily reversed by increasing fluid intake, but severe cases of dehydration require immediate medical attention.

A study explains that even small levels of dehydration can create headaches, lethargy, or just overall lack of alertness. Dehydration can also cause constipation.

What causes dehydration?

The immediate causes of dehydration include not enough water, too much water loss, or some combination of the two. Sometimes it is not possible to consume enough fluids because we are too busy, lack the facilities or strength to drink, or are in an area without potable water (while hiking or camping, for example). Additional causes of dehydration include:

• Diarrhea - the most common cause of dehydration and related deaths. The large intestine absorbs water from food matter, and diarrhea prevents this function, leading to dehydration.


• Vomiting - leads to a loss of fluids and makes it difficult to replace water by drinking it.


• Sweating - the body's cooling mechanism releases a significant amount of water. Hot and humid weather and vigorous physical activity can further increase fluid loss from sweating.


• Diabetes - high blood sugar levels cause increased urination and fluid loss. Tips for handling summer heat for people with diabetes.


• Frequent urination - usually caused by uncontrolled diabetes, but also can be due to alcohol and medications such as diuretics, antihistamines, blood pressure medications, and anti-psychotics.


• Burns - water seeps into damaged skin and the body loses fluids.

Who is at risk of dehydration?

Although dehydration can happen to anyone, some people are at a greater risk. Those highest at risk include:

• People in higher altitudes


• Athletes, especially those in endurance events such as marathons, triathlons, and cycling tournaments. Dehydration can undermine performance in sports, as this article explains.


• People with chronic illnesses such as diabetes, kidney disease, cystic fibrosis, alcoholism, and adrenal gland disorders


• Older adults, infants, and children. Dehydration in elderly people can be explained by brain malfunction, a study revealed. An article explains how drinking more water improved the health of elderly people.

What are the symptoms of dehydration?

The first symptoms of dehydration include thirst, darker urine, and decreased urine production. In fact, urine color is one of the best indicators of a person's hydration level - clear urine means you are well hydrated and darker urine means you are dehydrated. As the condition progresses to moderate dehydration, symptoms include:

• Dry mouth


• Lethargy


• Few or no tears when crying


• Weakness in muscles


• Headache


• Dizziness

Severe dehydration may be characterized by extreme versions of symptoms mentioned above as well as:

• Lack of sweating


• Sunken eyes


• Shriveled and dry skin


• Sunken fontanels (soft spots) in babies


• Low blood pressure


• Increased heart beat


• Fever


• Delirium


• Unconsciousness

How is dehydration diagnosed?

A physician will use both physical and mental exams to diagnose dehydration. A patient presenting symptoms such as disorientation, low blood pressure, rapid heart beat, fever, lack of sweat, and inelastic skin will usually be considered dehydrated.

Blood tests are often employed to test kidney function and to check sodium, potassium, and other electrolyte levels. Electrolytes are chemical ions that regulate hydration in the body and are crucial for nerve and muscle function. A urinalysis will provide very useful information for a dehydration diagnosis. In a dehydrated person, urine will be darker in color and more concentrated - containing a certain level of a compound called ketones.

To diagnose dehydration in infants, doctors usually check for a sunken soft spot on the skull. They may also look for a loss of sweat and certain muscle tone characteristics.

How is dehydration treated?

Dehydration must be treated by replenishing the fluid level in the body. This can be done by consuming clear fluids such as water, clear broths, frozen water or ice pops, or sports drinks (such as Gatorade). Some dehydration patients, however, will require intravenous fluids in order to rehydrate. People who are dehydrated should avoid drinks containing caffeine such as coffee, tea, and sodas. A study indicated that dehydrated children should be given fluids by mouth. Underlying conditions that are causing dehydration should also be treated with the appropriate medication. This may include anti-diarrhea medicines, anti-emetics (stop vomiting), and anti-fever medicines.

How can dehydration be prevented?

Prevention is really the most important treatment for dehydration. Consuming plenty of fluids and foods that have high water content (such as fruits and vegetables) should be enough for most people to prevent dehydration. People should be cautious about doing activities during extreme heat or the hottest part of the day, and all person who are exercising should make replenishing fluids a priority. Since the elderly and very young are often most at risk being dehydrated, special attention should be given to them to make sure they are receiving enough fluids.

Videos: Signs of dehydration - How to prevent it

Written by Peter Crosta M.A.
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today