> Table of Contents > Dehydration
Jerin Mathew, MD
Mony Fraer, MD, FACP, FASN
image BASICS
  • Dehydration is a state of negative fluid balance; strictly defined as free water deficiency
  • The two types of dehydration:
    • Water loss
    • Salt and water loss (combination of dehydration and hypovolemia)
  • Cause of 10% of all pediatric hospitalizations in the United States
  • Gastroenteritis, one of its leading causes, accounts to 13/1,000 children <5 years of age annually in the United States.
  • More than half a million hospital admissions annually in the United States for dehydration
  • Of hospitalized older persons, 7.8% have the diagnosis of dehydration (1).
  • Worldwide, ˜3 to 5 billion cases of acute gastroenteritis occur each year in children <5 years of age, resulting in nearly 2 million deaths.
  • Negative fluid balance occurs when ongoing fluid losses exceed fluid intake.
  • Fluid losses can be insensible (sweat, respiration), obligate (urine, stool), or abnormal (diarrhea, vomiting, osmotic diuresis in diabetic ketoacidosis).
  • Negative fluid balance can ultimately lead to severe intravascular volume depletion (hypovolemia) and ultimately end-organ damage from inadequate perfusion.
  • The elderly are at increased risk as kidney function, urine concentration, thirst sensation, aldosterone secretion, release of vasopressin, and renin activity are all significantly lowered with age.
  • Decreased intake
  • Increased output: vomiting, diarrheal illnesses, sweating, frequent urination
  • Third spacing of fluids: effusions, ascites, capillary leaks from burns, or sepsis
Some underlying causes of dehydration have a genetic component (diabetes), whereas others do not (gastroenteritis).
  • Children <5 years of age at highest risk
  • Elderly
  • Decreased cognition
  • Lack of access to water such as in critically sick intubated patients
  • Patient/parent education on the early signs of dehydration
  • Observing universal precautions (including hand hygiene)
Geriatric Considerations
A systematic approach in assessing risk factors is necessary for early prevention and management of dehydration in the elderly, especially those in long-term care facilities.
  • Hypo-/hypernatremia
  • Hypokalemia
  • Hypovolemic shock
  • Renal failure
Calculate % dehydration = (preillness weight - illness weight)/preillness weight × 100. Supplement this along with the ongoing fluid loss.

Clinical Finding (2)




Dehydration: children




Dehydration: adults




General condition: infants

Thirsty, alert, restless


Limp, cold, cyanotic extremities, may be comatose

General condition: older children

Thirsty, alert, restless

Alert, postural dizziness

Apprehensive, cold, cyanotic extremities, muscle cramps

Quality of radial pulse



Feeble or impalpable

Quality of respiration



Deep and rapid/tachypnea



Normal to low

Low (shock)

Skin turgor

Normal skin turgor

Reduced skin turgor, cool skin

Skin tenting, cool, mottled, acrocyanotic skin




Very Sunken





Mucous membranes



Very dry

Urine output



None passed in many hours

Anterior fontanelle



Markedly sunken

  • The most useful individual signs for identifying dehydration in children are prolonged capillary refill time, abnormal skin turgor, and abnormal respiratory pattern (3).
  • Vitals: pulse, BP, temperature
  • Orthostatic vital signs: Take BP and heart rate (HR) while supine, sitting, and standing.
    • Systolic BP decrease by 20, diastolic BP decrease by 10, or HR increase by 20 highly suggestive of hypovolemia (4)
  • Weight loss: <5%, 10%, or >15%
  • Mental status
  • Head: sunken anterior fontanelle (for infants)
  • Eyes: sunken, ± tear production
  • Mucous membranes: tacky, dry, or parched
  • Capillary refill: ranges from brisk to >3 seconds
  • Decreased intake: ineffective breastfeeding, inadequate thirst response, anorexia, malabsorption, metabolic disorder, obtunded state
  • Excessive losses: gastroenteritis, diarrhea, febrile illness, diabetic ketoacidosis, hyperglycemia, hyperosmolar hyperglycemic state, diabetes insipidus, intestinal obstruction, sepsis
Initial Tests (lab, imaging)
  • For mild dehydration: generally not necessary
  • For moderate to severe dehydration
    • Blood work, including electrolytes, BUN, creatinine, and glucose
    • Urinalysis (specific gravity, hematuria, glucosuria)
  • Imaging does not play a role in the diagnosis of dehydration, unless diagnosis of the specific medical condition causing the dehydration requires imaging.
  • In adults, there is evidence to support the use of inferior vena cava collapsibility as a surrogate marker for volume status.
Pediatric Considerations
Infants and the elderly may not concentrate urine maximally, so a nonelevated specific gravity should not be reassuring.

First Line
  • Oral rehydration is the first-line treatment in dehydrated children. If this is unsuccessful, use IV rehydration. If IV unobtainable, nasogastric (NG) rehydration can be considered (5).
  • Oral rehydration is the first-line treatment in dehydrated adults as long as they can tolerate fluids. Have a lower threshold for IV rehydration if needed.
  • If the patient is experiencing excessive vomiting, consider using an antiemetic.
  • Ondansetron (PO/IV) may be effective in decreasing the rate of vomiting, improving the success rate of oral hydration, preventing the need for IV hydration, and preventing the need for hospital admission (6,7).
  • Other antiemetics can be used.
Second Line
  • Loperamide may reduce the duration of diarrhea compared with placebo in children with mild to moderate dehydration (two randomized controlled trials [RCTs] yes, one RCT no).
  • In children ages 3 to 12 years with mild diarrhea and minimal dehydration, loperamide decreases diarrhea duration and frequency when used with oral rehydration.
Pediatric Considerations
Given a higher risk for serious adverse events, loperamide is not indicated for children <3 years of age with acute diarrhea.
  • For severe dehydration, critical care referral and ICU-level care may be warranted.
  • Surgical consultation for acute abdominal issues
For specific underlying causes of dehydration, such as intestinal obstruction or appendicitis
Admission Criteria/Initial Stabilization
  • Intractable vomiting/diarrhea
  • Electrolyte abnormalities
  • Hemodynamic instability
  • Inability to tolerate oral rehydration therapy (ORT)
  • Stabilize ABCs.
  • If mild dehydration, try ORT.
  • If excessive vomiting/severe dehydration with shock, start IV access and IV fluids immediately.
IV Fluids
  • Stage I
    • For moderate to severe dehydration in children: isotonic saline or Ringer lactate solution bolus of 10 to 20 mL/kg; may repeat up to 60 mL/kg; if still hemodynamically unstable, consider colloid replacement (blood, albumin, fresh frozen plasma) and address other causes for shock.
    • For moderate to severe hypovolemia in adults: isotonic saline or Ringer lactate 20 mL/kg/hr until normal state of consciousness returns/vital signs stabilize. Also consider colloid replacement if continued fluids required beyond 3 L.
  • Stage II: Replace fluid deficit along with maintenance over 48 hours. Fluid deficit = preillness weight - illness weight.
  • An alternative IV treatment option for moderate (10%) dehydration in children
    • Bolus with NS/LR at 20 mL/kg for 1 hour
    • Replete fluid deficit with D5 1/2 NS + 20 mEq KCl/L at 10 mL/kg for 8 hours (hours 2 to 9).
    • Replete 1.5 for maintenance fluids with D5 1/4 NS + 20 mEq/L of KCl for 16 hours (hours 10 to 24).
  • An alternative to IV fluids is hypodermoclysis, the SC infusion of fluids into the body.
    • Indications: hydration of patients with mild to moderate dehydration who do not tolerate oral intake because of cognitive impairment, severe dysphagia, advanced terminal illness, or intractable vomiting. It is also indicated to prevent dehydration, especially in frail elderly residents living in long-term care settings who reject the oral route for any reason; useful technique for patients with difficult IV access
    • Contraindications: severe dehydration or shock, patients with coagulopathy or receiving full anticoagulation, patients with severe generalized edema (anasarca) or congestive heart failure, and those with fluid overload (8)
Strict inputs and outputs: oral and IV input and output of urine and stool, which may include weighing wet diapers
Discharge Criteria
  • Input > output
  • Underlying etiology treated and improving
Activity as tolerated
  • If mild to moderate dehydration, the patient may be mobile without restrictions, although watch for orthostasis/falls.
  • If moderate to severe dehydration, bed rest.
Patient Monitoring
Ongoing surveillance for recurrence
  • Bland food such as bananas, rice, apples, toast (BRAT) diet
  • If diarrhea, avoid dairy for 48 hours after symptoms resolve. One review of weak RCTs and three of five subsequent RCTs found that lactose-free feeds reduced the duration of diarrhea in children with mild to severe dehydration, compared with lactose-containing feeds. However, two subsequent RCTs found no difference between lactose-free and lactose-containing feeds in duration of diarrhea.
  • Small frequent sips of room temperature liquids
  • For children, Pedialyte (liquid or popsicles)
  • Continue breastfeeding ad lib.
  • Patients should go to the nearest emergency facility or call 911 if they or their child feels faint or dizzy when rising from a sitting or lying position, becomes lethargic and/or confused, or complains of a rapid heart rate.
  • Patients should call their physician if they are unable to keep down any fluids, vomiting has been going on >24 hours in an adult or >12 hours in a child, diarrhea has lasted >2 days in an adult/child, or an infant/child is much less active than usual or is very irritable.
  • Patient information on dehydration: http://www.mayoclinic.org/diseases-conditions/dehydration/basics/definition/con-20030056
Self-limited if treated early; potentially fatal
1. Thomas DR, Cote TR, Lawhorne L, et al. Understanding clinical dehydration and its treatment. J Am Med Dir Assoc. 2008;9(5):292-301.
2. Gorelick MH, Shaw KN, Murphy KO. Validity and reliability of clinical signs in the diagnosis of dehydration in children. Pediatrics. 1997;99(5):E6.
3. Steiner MJ, DeWalt DA, Byerley JS. Is this child dehydrated? JAMA. 2004;291(22):2746-2754.
4. Lanier JB, Mote MB, Clay EC. Evaluation and management of orthostatic hypotension. Am Fam Physician. 2011;84(5):527-536.
5. Rouhani S, Meloney L, Ahn R, et al. Alternative rehydration methods: a systematic review and lessons for resource-limited care. Pediatrics. 2011;127(3):e748-e757.
6. Colletti JE, Brown KM, Sharieff GQ, et al. The management of children with gastroenteritis and dehydration in the emergency department. J Emerg Med. 2010;38(5):686-698.
7. Carter B, Fedorowicz Z. Antiemetic treatment for acute gastroenteritis in children: an updated Cochrane systematic review with meta-analysis and mixed treatment comparison in a Bayesian framework. BMJ Open. 2012;2(4):e000622.
8. Lopez JH, Reyes-Ortiz CA. Subcutaneous hydration by hypodermoclysis. Rev Clin Gerontol. 2010;20(2):105-113.
See Also
Oral Rehydration
  • E86.0 Dehydration
  • E87.1 Hypo-osmolality and hyponatremia
  • E86.1 Hypovolemia
Clinical Pearls
  • Dehydration is the result of a negative fluid balance and is a common cause of hospitalization in both children and the elderly.
  • Begin by assessing the level of dehydration and determining the underlying cause.
  • Treatment is directed at restoring fluid balance via oral rehydration (first-line) therapy or IV fluids and treating underlying causes.