Dehydration: Types, Causes and Treatment

Dehydration is defined as an excessive loss of body fluid. Dehydration occurs when more fluids are lost than taken in and the body doesn’t have enough water and other fluids to carry out its normal functions.

Three main types of dehydration based on type of fluid loss:

  1. Hypotonic or hyponatremic – primarily a loss of electrolytes, particularly sodium
  2. Hypertonic or hypernatremic – primarily a loss of water
  3. Isotonic or isonatremic – equal loss of water and electrolytes

Three types of dehydration based on severity:

  1. Mild – when the body has lost about 2% of it’s total fluid
  2. Moderate – when the total fluid loss reaches 5%
  3. Severe – when the body reaches 10% fluid loss, considered a emergency

In humans, the most commonly seen type of dehydration is isotonic (isonatraemic) dehydration, which equ

ates with hypovolemia, but the distinction of isotonic from hypotonic or hypertonic dehydration may be important when treating people who become dehydrated.


  • intense diarrhea
  • vomiting
  • fever
  • increased urination
  • excessive sweating
  • burns
  • inadequate intake of water during hot weather or exercise

People at Risk:

  • infants and children
  • older adults
  • people with chronic illness
  • endurance athletes
  • people living in high altitudes

Mild to moderate dehydration is likely to cause:

  • Dry, sticky mouth
  • Sleepiness or tiredness — children are likely to be less active than usual
  • Thirst
  • Decreased urine output — fewer than six wet diapers a day for infants and eight hours or more without urination for older children and teens
  • Few or no tears when crying
  • Muscle weakness
  • Headache
  • Dizziness or lightheadedness

Severe dehydration, a medical emergency, can cause:

  • Extreme thirst
  • Extreme fussiness or sleepiness in infants and children; irritability and confusion in adults
  • Very dry mouth, skin and mucous membranes
  • Lack of sweating
  • Little or no urination — any urine that is produced will be dark yellow or amber
  • Sunken eyes
  • Shriveled and dry skin that lacks elasticity and doesn’t “bounce back” when pinched into a fold
  • In infants, sunken fontanels — the soft spots on the top of a baby’s head
  • Low blood pressure
  • Rapid heartbeat
  • Fever
  • In the most serious cases, delirium or unconsciousness

Diagnostic tests:

  • blood tests
  • urinalysis


The only effective treatment for dehydration is to replace lost fluids and lost electrolytes. The best approach to dehydration treatment depends on your age, the severity of your dehydration and its cause.

  • Oral rehydration solution (ORS)
  • Fluid replacement through intravenous therapy
  • Treating the cause of dehydration

Nursing Considerations:

  1. Assess vital signs, noting peripheral pulses.
  2. Monitor blood pressure and invasive hemodynamic parameters.
  3. Strictly monitor intake and output. Observe the physical properties of the urine.
  4. Correctly infuse the right amount of IVF.
  5. Encourage small, frequent feedings.
  6. Provide frequent, oral care.
  7. Administer medications as prescribe.Photo credits:

Daisy Jane Antipuesto RN MN

Currently a Nursing Local Board Examination Reviewer. Subjects handled are Pediatric, Obstetric and Psychiatric Nursing. Previous work experiences include: Clinical instructor/lecturer, clinical coordinator (Level II), caregiver instructor/lecturer, NC2 examination reviewer and staff/clinic nurse. Areas of specialization: Emergency room, Orthopedic Ward and Delivery Room. Also an IELTS passer.

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