Dehydration

Injury	Disease	Nutrition	Poison

Symptoms	Surgery	Test	Special Topic

Skin turgor

Dehydration

Symptoms:

Dry or sticky mouth
Low or no urine output; concentrated urine appears dark yellow
Not producing tears
Sunken eyes
Markedly sunken fontanelles (the soft spot on the top of the head) in an infant
Lethargic or comatose (with severe dehydration)

In addition to the symptoms of actual dehydration, you may also have vomiting, diarrhea, or the feeling that you "can't keep anything down", all of which could be causing the dehydration.
Signs and tests:

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A physical examination may also show signs of:

Low blood pressure
Blood pressure that drops when you go from lying down to standing
Rapid heart rate
Poor skin turgor -- the skin may lack its normal elasticity and sag back into position slowly when pinched up into a fold by the doctor; normally, skin springs right back into position
Delayed capillary refill
Shock

Tests include:

Blood chemistries (to check electrolytes, especially sodium, potassium, and bicarbonate levels)
Urine specific gravity (a high specific gravity indicates significant dehydration)
BUN (blood urea nitrogen -- may be elevated with dehydration)
Creatinine (may be elevated with dehydration)
Complete Blood Count (CBC) to look for signs of concentrated blood

Other tests may be done to determine the specific cause of the dehydration (for example, a blood sugar to check for diabetes).
References:

Porter SC. The value of parental report for diagnosis and management of dehydration in the emergency department. Ann Emerg Med. 2003; 41(2): 196-205.

Guerrant RL. Practice guidelines for the management of infectious diarrhea. Clin Infec Dis. 2001; 32(3): 331-351.

Committee on Sports Medicine and Fitness. American Academy of Pediatrics. Climatic heat stress and the exercising child and adolescent. Pediatrics. 2000; 106(1 Pt 1): 158-159.