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A diagnosis of dehydration is frequently based upon clinical signs and symptoms, and appropriate treatment is given. Laboratory testing is typically not required for mild to moderate dehydration, but a variety of non-laboratory evaluations may be used to assess an individual with more serious symptoms.

Non-Laboratory Evaluations

These may include an evaluation of:

  • Urine output and production of tears
  • Examination of dryness of skin and mucous membranes
  • Breathing rate – is it rapid?
  • Heart rate – is it rapid?
  • Blood pressure – is it low?
  • Skin turgor – when a fold of skin is pinched and then released, does it bounce back in shape or only slowly relax?
  • Capillary refill rate – is it slower than normal?
  • Do eyes appear sunken and, if so, to what degree?
  • State of consciousness

Laboratory Tests

In cases of severe dehydration, laboratory testing is frequently ordered to identify electrolyte and acid-base imbalances, to evaluate kidney function, and general health status. If imbalances and/or organ dysfunction are found, then serial testing may be performed to monitor the person over time and their response to treatment. Testing may include:

If the cause of dehydration is apparent, then usually no other testing is necessary. However, a variety of tests may be performed when the cause is unknown, to diagnose and address underlying conditions, such as those associated with prolonged diarrhea and/or vomiting.

A wide variety of other tests may be done depending on what is suspected to be the underlying cause of the signs and symptoms, such as:

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