• Dehydration is a deficiency in total body water (1).
  • The two types of dehydration:
    • Water loss
    • Salt and water loss (combination of dehydration and hypovolemia)


Dehydration is associated with increased mortality and morbidity and is prevalent in the health-care setting and in the community (1); responsible for 10% of all pediatric hospitalizations United States (2)

In the United States, admission rate for dehydration and related diagnosis has remained stable at approximately 130 per 100,000 for the general population. Two observational studies in Europe have shown that 37–46% of patients aged >65 years presented to major hospitals with dehydration (1).

Several retrospective studies have sought to evaluate the prevalence of dehydration occurring after hospital admission, with current estimates of 2–3.5% of patients meeting dehydration criteria (1).

Etiology and Pathophysiology

  • Body water can be lost through the skin, lungs, kidneys, and gastrointestinal tract.
  • Negative fluid balance occurs when ongoing fluid losses exceed fluid intake.
  • Fluid losses can be insensible (sweat, respiration), obligate (urine, stool), or abdominal (diarrhea, vomiting, osmotic diuresis in diabetic ketoacidosis).
  • Negative fluid balance can lead to hypovolemia (severe intravascular volume depletion) and end-organ damage from inadequate perfusion.
  • “Third spacing” of fluids can occur in patients with effusions, ascites, capillary leaks (e.g., burns), or sepsis.

Geriatric Considerations
The elderly are at increased risk as kidney function, urine concentration, thirst sensation, aldosterone secretion, release of vasopressin, and renin activity all significantly decline with age.

Some cases of dehydration have a genetic component (diabetes), whereas others do not (gastroenteritis).

Risk Factors

  • Children <5 years of age at highest risk (2)
  • Elderly
  • Acute or chronic illness
  • Decreased cognition or mental status
  • Lack of access to water
  • Increased exertion in high temperature
  • Taking certain medications (e.g., diuretics)

General Prevention

  • Patient and/or parent education on early signs of dehydration
  • Provide preferred beverages (especially in illness).
  • Universal precautions (including hand hygiene)

Clinical FindingMildModerateSevere
Dehydration: children5–10%10–15%>15%
Dehydration: adults3–5%5–10%>10%
General condition: infantsThirsty, alert, restlessLethargic/drowsyLimp, cold, cyanotic extremities, may be comatose
General condition: older childrenThirsty, alert, restlessAlert, postural dizzinessApprehensive, cold, cyanotic extremities, muscle cramps
Quality of radial pulseNormalThready/weakFeeble or impalpable
Quality of respirationNormalDeepDeep and rapid/tachypnea
BPNormalNormal to lowLow (shock)
Skin turgorNormal skin turgorReduced skin turgor, cool skinSkin tenting, cool, mottled, acrocyanotic skin
EyesNormalSunkenVery sunken
Mucous membranesMoistDryVery dry
Urine outputNormalReducedNone passed in many hours
Anterior fontanelleNormalSunkenMarkedly sunken

Commonly Associated Conditions

  • Hyponatremia
  • Hypernatremia
  • Hypokalemia
  • Hyperglycemia
  • Hypovolemic shock
  • Renal failure
  • Rhabdomyolysis
  • Heat illness

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