Dehydration is the loss of water and salts essential for normal body function. It occurs when the body loses more fluid than it takes in.

Young and middle-aged adults who drink when thirsty generally maintain fluidbalance. Children need more water because they expend more energy, but most children who drink when thirsty get as much water as they need. Adults over the age of 60 who drink only when thirsty probably get only about 90% of the fluid they need.

Dehydration is a major cause of infant illness and death. Dehydration can occur in children who have stomach flu characterized by vomiting and diarrhea, or who cannot or will not take enough fluids to compensate for excessive losses associated with fever and sweating of acute illness. An infant can become dehydrated only hours after becoming ill.

When the body's fluid supply is severely depleted, hypovolemic shock is likely to occur. This condition, which is also called physical collapse, is characterized by pale, cool, clammy skin; rapid heartbeat; and shallow breathing. Blood pressure sometimes drops so low it cannot be measured, and skin at the knees and elbows may become blotchy. Anxiety, restlessness, and thirst increase. After the patient's temperature reaches 107°F (41.7°C), damage tothe brain and other vital organs occurs quickly.

Strenuous activity, excessive sweating, high fever, and prolonged vomiting ordiarrhea are common causes of dehydration. So are staying in the sun too long, not drinking enough fluids, and visiting or moving to a warm region whereit doesn't often rain. Alcohol, caffeine, and diuretics or other medicationsthat increase the amount of fluid excreted can cause dehydration.

Reduced fluid intake can be a result of appetite loss associated with acute illness, excessive urination, nausea, bacterial or viral infection or inflammation of the pharynx, or inflammation of the mouth caused by illness, infection, irritation, or vitamin deficiency.

Other conditions that can lead to dehydration include disease of the adrenalglands, diabetes mellitus, eating disorders, kidney disease, and chronic lung disease.

An infant who does not wet a diaper in an eight-hour period is dehydrated. The soft spot on the baby's head (fontanel) may be depressed. Symptoms of dehydration at any age include cracked lips, dry or sticky mouth, lethargy, and sunken eyes. A person who is dehydrated cries without shedding tears and does not urinate very often. The skin is less elastic than it should be and is slowto return to its normal position after being pinched. Dehydration can causeconfusion, constipation, discomfort, drowsiness, fever, and thirst. The skinturns pale and cold, the mucous membranes lining the mouth and nose lose their natural moisture. The pulse sometimes races and breathing becomes rapid. Significant fluid loss can cause serious neurological problems.

Increased fluid intake and replacement of lost electrolytes are usually sufficient to restore fluid balances in patients who are mildly or moderately dehydrated. In these cases, just drinking water may be all that is needed. Adultswho need to replace lost electrolytes may drink sports beverages (e.g. Gatorade or Recharge) or consume a little additional salt. Parents should follow label instructions when giving children Pedialyte or other commercial productsrecommended to relieve dehydration. Children who are dehydrated should receive only clear fluids for the first 24 hours.

A child who is vomiting should sip one or two teaspoons of liquid every 10 minutes. A child who is less than a year old and who is not vomiting should begiven one tablespoon of liquid every 20 minutes. A child who is more than oneyear old and who is not vomiting should take two tablespoons of liquid every30 minutes. A baby who is being breast-fed should be given clear liquids fortwo consecutive feedings before breastfeeding is resumed. A bottle-fed babyshould be given formula diluted to half its strength for the first 24 hours after developing symptoms of dehydration.

Children and adults can gradually return to their normal diet after they havestopped vomiting and no longer have diarrhea. Bland foods should be reintroduced first, with other foods added as the digestive system is able to tolerate them. Milk, ice cream, cheese, and butter should not be eaten until 72 hours after symptoms have disappeared.

Severe dehydration can require hospitalization and intravenous fluid replacement. If an individual's blood pressure drops enough to cause shock, medical treatment is usually required. A doctor should be notified whenever aninfant or child exhibits signs of dehydration or a parent is concerned that astomach virus or other acute illness may lead to dehydration.

A doctor should also be notified if:

  • A child less than three months old develops a fever higher than 100°F (37.8°C)
  • A child more than three months old develops a fever higher than 102°F (38.9°C)
  • Symptoms of dehydration worsen
  • An individual urinates very sparingly or does not urinate at all during a 6-hour period
  • Dizziness, listlessness, or excessive thirst occur
  • A person who is dietingand using diuretics loses more than 3 lbs (1.3 kg) in a day or more than 5 lbs (2.3 kg) a week.

If dehydration is caused by vomiting or diarrhea, medications may be prescribed to resolve these symptoms. Patients who are dehydrated due to diabetes, kidney disease, or adrenal gland disorders must receive treatment for these conditions as well as for the resulting dehydration.

Mild dehydration rarely results in complications. If the cause is eliminatedand lost fluid is replaced, mild dehydration can usually be cured in 24-48 hours.

Vomiting and diarrhea that continue for several days without adequate fluid replacement can be fatal. The risk of life-threatening complications is greater for young children and the elderly. However, dehydration that is rapidly recognized and treated has a good outcome.

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