Dehydration

Medical Author: Benjamin C. Wedro, MD, FAAEM
Medical Editor: Melissa Conrad Stöppler, MD

• What is dehydration?
• What causes dehydration?
• What are the signs and symptoms of dehydration?
• How is dehydration diagnosed?
• How is dehydration treated?
• Can I treat dehydration at home?
• What are the complications of dehydration?
• How can dehydration be prevented?
• Dehydration At A Glance

Exercise-Associated Hyponatremia: Who's at Risk? Medical Author: Melissa Conrad Stöppler, MD Medical Editor: William C. Shiel Jr., MD, FACP, FACR We've all learned that fluid replacement is critical to replace fluids lost when exercising, but drinking pure water exclusively isn't the safest choice for those who participate in very strenuous or long-duration exercise. When significant amounts of fluid are lost through high-intensity exercise, replacement with water alone can lead to a chemical imbalance in the body and deficiencies in electrolytes, which are nutrients critical for organ functioning. The electrolytes in our body include sodium, potassium, chloride, calcium and phosphate, but sodium is the substance of most concern when replacing fluids lost through exercising. Hyponatremia is a condition in which the body's stores of sodium are too low, and this condition can result from drinking extreme amounts of water. Hyponatremia can lead to confusion, lethargy, agitation, seizures, and in extreme cases, even death. Early symptoms are nonspecific and subtle and may include disorientation, nausea, or muscle cramps. The symptoms of hyponatremia may also mimic those of dehydration, so athletes experiencing these symptoms may be given more water to drink, further worsening the condition. Learn how dehydration symptoms may mimic hyponatremia symptoms » Top Searched Dehydration Terms: definition, athletes, elderly, baby, shock, pregnancy, diarrhea, vomiting, dry mouth

What is dehydration?

The majority of the body is made up of water, with up to 75% of the body's weight due to H2O. Most of the water is found within the cells of the body (intracellular space). The rest is found in the so-called extracellular space, which consists of the blood vessels (intravascular space) and the spaces between cells (interstitial space).

Total body water = intracellular space + intravascular space + interstitial space

Dehydration occurs when the amount of water leaving the body is greater than the amount being taken in. The body is very dynamic and always changing. This is especially true with water in the body. We lose water routinely when we:

• breathe,
  
  
• as humidified air leaves the body,
  
  
• when we sweat to cool the body, and
  
  
• when we urinate or have a bowel movement to rid the body of waste products.

In a normal day, a person has to drink a significant amount of water to replace this routine loss.

If intravascular (within the blood vessels) water is lost, the body can compensate somewhat by shifting water from cells into the blood vessels, but this is a very short-term solution. Signs and symptoms of dehydration will occur quickly if the water is not replenished.

The body is able to monitor the amount of fluid it needs to function. The thirst mechanism signals the body to drink water when the body is dry. As well, hormones like anti-diuretic hormone (ADH) work with the kidney to limit the amount of water lost in the urine when the body needs to conserve water.

From the Doctors at MedicineNet.com

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