Exams and Tests

The doctor may perform a variety of simple tests at the examination or send blood or urine samples to the laboratory. Through tests and examination, the doctor will try to identify the underlying cause or causes that led to the dehydration.

• Vital signs
  
  
  • Fever, increased heart rate, decreased blood pressure, and faster breathing are signs of potential dehydration and other illnesses.
    
    
  • Taking the pulse and blood pressure while the person is lying down and then after standing up for 1 minute can help determine the degree of dehydration. Normally, when you have been lying down and then stand up, there is a small drop in blood pressure for a few seconds. The heart rate speeds up, and blood pressure goes back to normal. However, when there is not enough fluid in the blood because of dehydration and the heart rate speeds up, not enough blood is getting to the brain. The brain senses this condition. The heart beats faster, and if you are dehydrated, you feel dizzy and faint after standing up.
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• Urinalysis
  
  
  • The color and clarity of urine, the urine specific gravity (the mass of urine is compared with that of equal amounts of distilled water), and the presence of ketones (carbon compounds—a sign the body is dehydrated) in the urine may all help to indicate the degree of dehydration.
    
    
  • Increased glucose in the urine may lead to a diagnosis of diabetes or indicate loss of diabetic control and a cause for the dehydration.
    
    
  • Excessive protein may signal kidney problems.
    
    
  • Signs of infections or other diseases, such as liver disease, may be found.
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• Blood chemistries
  
  
  • The amount of salts (sodium and potassium) and sugar as well as indicators of kidney function (BUN and creatinine) may be important to evaluate the degree of dehydration and possible causes.
    
    
  • A complete blood count (CBC) may be ordered if the doctor thinks an underlying infection is causing the dehydration. Other blood tests, such as liver function tests, may be indicated to find causes of the symptoms.