Dehydration: Symptoms, Complaints, Signs

The symptoms and complaints of dehydration (fluid deficiency) are based on whether the body has lost mostly water, sodium, or both (in equal amounts).

The following symptoms and complaints may indicate dehydration:

  • Isotonic dehydration
    • Functional oliguria (< 500 ml urine/day).
    • Hypovolemic symptoms (symptoms of a decrease in the amount of blood circulating, i.e., in the bloodstream)
      • Thirst (occurs when water loss exceeds 0.5% of body weight)
      • Hypotension (low blood pressure)
      • Tendency to collapse
      • Tachycardia (heartbeat too fast: > 100 beats per minute).
  • Hypotonic dehydration
    • Hypovolemic symptoms as in “isotonic dehydration”; the tendency to collapse is more pronounced
    • Cerebral (“affecting the brain“) symptoms.
      • Cephalgia (headache)
      • Delir-like states (state of confusion).
      • Somnolence (disturbance of consciousness)
      • Cerebral spasms
    • Annotation:
      • The osmotic pressure in the extracellular space is decreased. As a result, there is a shift of water from the extracellular space into the cells. Thus, additional water is removed from the intravascular space (fluid space within the blood vessels). Therefore, hypovolemic symptoms such as tachycardia and hypotension occur earlier than in isotonic dehydration.
  • Hypertonic dehydration
    • Possibly fever
    • Hypovolemic symptoms are absent or are not very pronounced
    • Oliguria (< 500 ml urine/day).
    • Severe thirst
    • Standing skin folds
    • Dry skin and mucous membranes
    • Cerebral (“affecting the brain“) symptoms.
      • Cephalgia (headache)
      • Delir-like states (state of confusion).
      • Somnolence (disturbance of consciousness)
      • Cerebral spasms
    • Note: The circuit remains stable for a relatively long time!

Depending on the severity of dehydration, the symptoms and complaints can be classified as follows:

  • Mild dehydration
    • Thirst
    • Skin and mucous membranes are slightly dry
    • Concentrated urine (clearly colored urine).
  • Moderate dehydration
    • Pronounced dryness of skin and mucous membranes.
    • Sunken eyes
    • Oliguria (< 400 ml urine/day)
    • Tachycardia (rapid heartbeat)
  • Severe dehydration
    • Hypotension (low blood pressure)
    • Standing skin folds
    • Decreased skin perfusion (skin blood flow)
  • Shock
    • Disturbances of consciousness such as lethargy, delir-like states (confusion).
    • Circulatory insufficiency