Dehydration  

Causes, incidence, and risk factors
Dehydration can be caused by excessive loss of water from the body as in:
vomiting
diarrhea (especially well recognized in cholera)
excessive urine output (polyuria)
sweating, excessive
Dehydration can also occur from inadequate intake as in:
nausea
stomatitis or pharyngitis
acute illness with loss of appetite
Dehydration in children is most often a combination of both as in:
stomach flu with vomiting and diarrhea
acute illness where the child refuses fluids and loses excessive fluid through sweating with fever
Fluid losses up to 5% are considered mild; up to 10% are considered moderate; and up to 15% are considered severe. Severe dehydration can result in cardiovascular collapse and death if not treated quickly.

Prevention
Parents should consider the possibility of dehydration developing any time their child is ill. If you believe that dehydration is developing, they should consult the health care provider before the child becomes moderately or severely dehydrated. A few simple measures may prevent the development of severe dehydration.

Always provide adequate fluids during an illness, and pay attention to both the intake and output of fluid. For infants and young children, specific solutions (such as Pedialyte) are available that provide the right amount of electrolytes to prevent derangements of serum chemistries.

Symptoms
excessive loss of fluid through vomiting or excessive, urine, stools or sweating
poor intake of fluids
sunken eyes
markedly sunken fontanelles in an infant
dry or sticky mucus membranes in the mouth
the skin may lack its normal elasticity and sag back into position slowly when pinched up into a fold (poor skin turgor)
decreased or absent urine output (oliguria or anuria)
decreased tears
 

Signs and tests
Physical examination may also show signs of:
low blood pressure (hypotension)
rapid heart rate (tachycardia)
shock

Treatment
Oral rehydration may be sufficient for mild dehydration. Intravenous fluids and hospitalization may be necessary for moderate to severe dehydration. The health care provider must also determine and treat the cause of the dehydration.

Prognosis
Rapid recognition and treatment of dehydration results in a good outcome.

Complications
Untreated severe dehydration may result in seizures, permanent brain damage, or death.