Description

• Dehydration is a pathologic state of negative fluid balance in the body. Severity is generally expressed as a percentage of body weight. Mild, moderate, and severe dehydration correspond to volume loss of <5%, 5–10%, and >10%, respectively.
• Dehydration can also be classified as isotonic (Sodium [Na] 130 to 150 mmol/L), hypotonic (Na <130 mmol/L), or hypertonic (Na >150 mmol/L).
• Dehydration can be the result of a wide range of illnesses.
• Accurate clinical recognition and classification of dehydration determines rehydration treatment options.

Epidemiology

• Globally, dehydration from diarrheal illness is one of the leading causes of mortality in children <5 years old.
• Incidence of moderate to severe dehydration in the United States has declined since the introduction of routine rotavirus immunization.
• Despite a reduction in morbidity attributed to routine rotavirus vaccination, >100,000 children per year are hospitalized in the United States for dehydration from diarrheal illness.

Pathophysiology

Dehydration is caused by either excessive fluid and salt losses or inadequate intake of fluids.

Etiology

• Common sources of fluid loss include
  • GI losses: vomiting, diarrhea (most common cause of dehydration in pediatric patients)
  • Renal losses: diabetes mellitus, diabetes insipidus, diuretics
  • Insensible losses: sweating, fever, tachypnea, increased ambient temperature, large burns
• Common causes of inadequate fluid intake include
  • Pain from stomatitis, pharyngitis, herpangina, oral trauma
  • Anorexia or malaise
  • Altered mental status
  • Inadequate access to fluids or neglect