- Author: Lennox H Huang, MD, FAAP; Chief Editor: Timothy E Corden, MD more...
No definitive laboratory test for dehydration is available. Laboratory data are generally not required if the etiology is apparent and mild-to-moderate dehydration is present.
With severe dehydration, the following laboratory studies are suggested:
Serum sodium should be determined because hyponatremia (< 130 mEq/L) and hypernatremia (>150 mEq/L) require specific treatment regimens.
Potassium may be elevated (eg, congenital adrenal hyperplasia, renal failure) or low (eg, pyloric stenosis, alkalosis).
Chloride may be low in pyloric stenosis (eg, hypochloremic, hypokalemic, or metabolic alkalosis).
Poor tissue perfusion in dehydration results in production of lactic acid. Bicarbonate is consumed as lactic acid levels increase. In diabetic ketoacidosis (DKA), ketoacids also consume bicarbonate. Bicarbonate levels can also be reduced because of loss of bicarbonate in diarrheal stools. Low bicarbonate levels have been correlated with increased severity of dehydration in some studies.
Glucose may be dangerously low because of poor intake or extremely elevated in DKA.
BUN and creatinine levels may be elevated because of renal hypoperfusion.
Urine specific gravity may be elevated in patients with dehydration but should not be relied on because it is not an accurate diagnostic test for dehydration.  Further caution should be used in the setting of diabetes insipidus, in which the urine is dilute with low specific gravity, even in patients who are dehydrated.
Urinalysis may show findings of DKA (eg, ketones, glucose).
Electrolyte analysis of any fluid that is lost (eg, urine, stool, gastric fluid) can be performed to further refine the composition of replacement fluids after providing acute fluid resuscitation.
If severe dehydration is present, peripheral intravenous line insertion may be difficult. The preferred sites for initial insertion attempts include the basilic and cephalic veins in the antecubital fossa and the saphenous veins near the ankle. Transillumination of the insertion site with a fiberoptic light source may be used to facilitate locating the desired vein.
If peripheral intravenous access cannot be rapidly achieved (< 90 s) in a child with severe dehydration and shock, intraosseous cannulation should be attempted. If the child is not in extremis, more time may be taken to establish central venous access percutaneously (eg, femoral, subclavian, internal, external jugular).
Intraosseous cannulation can be easily and rapidly achieved in children younger than 6 years. Specially designed intraosseous infusion needles or Jamshidi-type bone marrow aspiration needles may be used. Short large-bore spinal needles may also be used but often bend during placement. The ideal site of insertion is the anteromedial surface of the tibia, 1-3 cm below the anterior tibial tuberosity. Care must be taken to avoid injury to the physeal growth plate.
An orogastric/nasogastric tube may be inserted to facilitate enteral rehydration in children with mild-to-moderate dehydration. These tubes should be considered to assist in the nutritional recovery of children who are critically ill or severely dehydrated.
Bettari L, Fiuzat M, Shaw LK, Wojdyla DM, Metra M, Felker GM, et al. Hyponatremia and long-term outcomes in chronic heart failure--an observational study from the Duke Databank for Cardiovascular Diseases. J Card Fail. 2012 Jan. 18(1):74-81. [Medline].
Guarner J, Hochman J, Kurbatova E, Mullins R. Study of outcomes associated with hyponatremia and hypernatremia in children. Pediatr Dev Pathol. 2011 Mar-Apr. 14(2):117-23. [Medline].
Zaki SA, Mondkar J, Shanbag P, Verma R. Hypernatremic dehydration due to lactation failure in an exclusively breastfed neonate. Saudi J Kidney Dis Transpl. 2012 Jan. 23(1):125-8. [Medline].
Arora SK. Hypernatremic Disorders in the Intensive Care Unit. J Intensive Care Med. 2011 May 16. [Medline].
Colletti JE, Brown KM, Sharieff GQ, Barata IA, Ishimine P. The Management of Children with Gastroenteritis and Dehydration in the Emergency Department. J Emerg Med. 2009 Apr 2. [Medline].
Parkin PC, Macarthur C, Khambalia A, Goldman RD, Friedman JN. Clinical and Laboratory Assessment of Dehydration Severity in Children With Acute Gastroenteritis. Clin Pediatr (Phila). 2009 Jun 1. [Medline].
Koster C, Klingelhöfer D, Groneberg DA, Schwarzer M. Rotavirus - Global research density equalizing mapping and gender analysis. Vaccine. 2016 Jan 2. 34 (1):90-100. [Medline].
Cheuvront SN, Kenefick RW, Montain SJ, Sawka MN. Mechanisms of aerobic performance impairment with heat stress and dehydration. J Appl Physiol. 2010 Dec. 109(6):1989-95. [Medline].
[Guideline] Goldman RD, Friedman JN, Parkin PC. Validation of the clinical dehydration scale for children with acute gastroenteritis. Pediatrics. 2008 Sep. 122(3):545-9. [Medline].
Steiner MJ, DeWalt DA, Byerley JS. Is this child dehydrated?. JAMA. 2004 Jun 9. 291(22):2746-54. [Medline].
Steiner MJ, Nager AL, Wang VJ. Urine specific gravity and other urinary indices: inaccurate tests for dehydration. Pediatr Emerg Care. 2007 May. 23(5):298-303. [Medline].
Brandt KG, de Castro Antunes MM, da Silva GA. Acute diarrhea: evidence-based management. J Pediatr (Rio J). 2015 Nov-Dec. 91 (6 Suppl 1):S36-43. [Medline].
Kumar R, Kumar P, Aneja S, Kumar V, Rehan HS. Safety and efficacy of low-osmolarity ORS vs. modified rehydration solution for malnourished children for treatment of children with severe acute malnutrition and diarrhea: a randomized controlled trial. J Trop Pediatr. 2015 Dec. 61 (6):435-41. [Medline].
Atherly-John YC, Cunningham SJ, Crain EF. A randomized trial of oral vs intravenous rehydration in a pediatric emergency department. Arch Pediatr Adolesc Med. 2002 Dec. 156(12):1240-3. [Medline].
Hartling L, Bellemare S, Wiebe N, Russell K, Klassen TP, Craig W. Oral versus intravenous rehydration for treating dehydration due to gastroenteritis in children. Cochrane Database Syst Rev. 2006 Jul 19. 3:CD004390. [Medline].
Danewa AS, Shah D, Batra P, Bhattacharya SK, Gupta P. Oral ondansetron in management of dehydrating diarrhea with vomiting in children aged 3 months to 5 years: a randomized controlled trial. J Pediatr. 2015 Dec 1. [Medline].
Freedman SB, Adler M, Seshadri R, Powell EC. Oral ondansetron for gastroenteritis in a pediatric emergency department. N Engl J Med. 2006 Apr 20. 354(16):1698-705. [Medline].
Uhlig U, Pfeil N, Gelbrich G, et al. Dimenhydrinate in children with infectious gastroenteritis: a prospective, RCT. Pediatrics. 2009 Oct. 124(4):e622-32. [Medline].
Shanley L, Mittal V, Flores G. Preventing dehydration-related hospitalizations: a mixed-methods study of parents, inpatient attendings, and primary care physicians. Hosp Pediatr. 2013 Jul. 3(3):204-11. [Medline].
Adrogue HJ, Madias NE. Hypernatremia. N Engl J Med. 2000 May 18. 342(20):1493-9. [Medline].
Bellemare S, Hartling L, Wiebe N, et al. Oral rehydration versus intravenous therapy for treating dehydration due to gastroenteritis in children: a meta-analysis of randomised controlled trials. BMC Med. 2004 Apr 15. 2:11. [Medline]. [Full Text].
Bender BJ, Ozuah PO, Crain EF. Oral rehydration therapy: is anyone drinking?. Pediatr Emerg Care. 2007 Sep. 23(9):624-6. [Medline].
Bhatnagar S, Bahl R, Sharma PK, et al. Zinc with oral rehydration therapy reduces stool output and duration of diarrhea in hospitalized children: a randomized controlled trial. J Pediatr Gastroenterol Nutr. 2004 Jan. 38(1):34-40. [Medline].
Choice Study Group. Multicenter, randomized, double-blind clinical trial to evaluate the efficacy and safety of a reduced osmolarity oral rehydration salts solution in children with acute watery diarrhea. Pediatrics. 2001 Apr. 107(4):613-8. [Medline].
Dale J. Oral rehydration solutions in the management of acute gastroenteritis among children. J Pediatr Health Care. 2004 Jul-Aug. 18(4):211-2. [Medline].
Duggan C, Fontaine O, Pierce NF, et al. Scientific rationale for a change in the composition of oral rehydration solution. JAMA. 2004 Jun 2. 291(21):2628-31. [Medline].
Duggan C, Refat M, Hashem M, et al. How valid are clinical signs of dehydration in infants?. J Pediatr Gastroenterol Nutr. 1996 Jan. 22(1):56-61. [Medline].
Duke T, Molyneux EM. Intravenous fluids for seriously ill children: time to reconsider. Lancet. 2003 Oct 18. 362(9392):1320-3. [Medline].
Fonseca BK, Holdgate A, Craig JC. Enteral vs intravenous rehydration therapy for children with gastroenteritis: a meta-analysis of randomized controlled trials. Arch Pediatr Adolesc Med. 2004 May. 158(5):483-90. [Medline].
Gorelick MH, Shaw, KN, Murphy, KO. Validity and reliability of clinical signs in the diagnosis of dehydration in children. Pediatrics. 1997. May;(5):99:E6. [Medline].
Holliday M. The evolution of therapy for dehydration: should deficit therapy still be taught?. Pediatrics. 1996 Aug. 98(2 Pt 1):171-7. [Medline].
Holliday MA, Friedman AL, Segar WE, et al. Acute hospital-induced hyponatremia in children: a physiologic approach. J Pediatr. 2004 Nov. 145(5):584-7. [Medline].
Holliday MA, Friedman AL, Wassner SJ. Extracellular fluid restoration in dehydration: a critique of rapid versus slow. Pediatr Nephrol. 1999 May. (4):292-7. [Medline].
Hoorn EJ, Geary D, Robb M, et al. Acute hyponatremia related to intravenous fluid administration in hospitalized children: an observational study. Pediatrics. 2004 May. 113(5):1279-84. [Medline].
King CK, Glass R, Bresee JS, et al. Managing acute gastroenteritis among children: oral rehydration, maintenance, and nutritional therapy. MMWR Recomm Rep. 2003 Nov 21. 52(RR-16):1-16. [Medline].
Miyasaka K, Shimizu N, Kojima J. Recent trends in pediatric fluid therapy. Methods Find Exp Clin Pharmacol. 2004 May. 26(4):287-94. [Medline].
Moritz ML, Ayus JC. Preventing neurological complications from dysnatremias in children. Pediatr Nephrol. 2005 Dec. 20(12):1687-700. [Medline].
Moritz ML, Ayus JC. Prevention of hospital-acquired hyponatremia: a case for using isotonic saline. Pediatrics. 2003 Feb. 111(2):227-30. [Medline].
Moritz ML, Manole MD, Bogen DL, Ayus JC. Breastfeeding-associated hypernatremia: are we missing the diagnosis?. Pediatrics. 2005 Sep. 116(3):e343-7. [Medline].
Murphy C, Hahn S, Volmink J. Reduced osmolarity oral rehydration solution for treating cholera. Cochrane Database Syst Rev. 2004. CD003754. [Medline].
Nager AL, Wang VJ. Comparison of nasogastric and intravenous methods of rehydration in pediatric patients with acute dehydration. Pediatrics. 2002 Apr. 109(4):566-72. [Medline].
Nalin DR, Hirschhorn N, Greenough W, et al. Clinical concerns about reduced-osmolarity oral rehydration solution. JAMA. 2004 Jun 2. 291(21):2632-5. [Medline].
Ozuah PO, Avner JR, Stein RE. Oral rehydration, emergency physicians, and practice parameters: a national survey. Pediatrics. 2002 Feb. 109(2):259-61. [Medline].
Phin SJ, McCaskill ME, Browne GJ, Lam LT. Clinical pathway using rapid rehydration for children with gastroenteritis. J Paediatr Child Health. 2003 Jul. 39(5):343-8. [Medline].
Playfor SD. Hypotonic intravenous solutions in children. Expert Opin Drug Saf. 2004 Jan. 3(1):67-73. [Medline].
Reid SR, Bonadio WA. Outpatient rapid intravenous rehydration to correct dehydration and resolve vomiting in children with acute gastroenteritis. Ann Emerg Med. 1996 Sep. 28(3):318-23. [Medline].
Santosham M, Keenan EM, Tulloch J, et al. Oral rehydration therapy for diarrhea: an example of reverse transfer of technology. Pediatrics. 1997 Nov. 100(5):E10. [Medline].
Sarnaik AP, Meert K, Hackbarth R, Fleischmann L. Management of hyponatremic seizures in children with hypertonic saline: a safe and effective strategy. Crit Care Med. 1991. Jun;19(6):758-62. [Medline].
Spandorfer PR, Alessandrini EA, Joffe MD, et al. Oral versus intravenous rehydration of moderately dehydrated children: a randomized, controlled trial. Pediatrics. 2005 Feb. 115(2):295-301. [Medline].
Wathen JE, MacKenzie T, Bothner JP. Usefulness of the serum electrolyte panel in the management of pediatric dehydration treated with intravenously administered fluids. Pediatrics. 2004 Nov. 114(5):1227-34. [Medline].
|Symptom/Sign||Mild Dehydration||Moderate Dehydration||Severe Dehydration|
|level of consciousness||Alert||Lethargic||Obtunded|
|Capillary refill*||2 s||2-4 s||>4 s, cool limbs|
|Mucous membranes||Normal||Dry||Parched, cracked|
|Heart rate||Slightly increased||Increased||Very increased|
|Respiratory rate/pattern*||Normal||Increased||Increased and hyperpnea|
|Blood pressure||Normal||Normal, but orthostasis||Decreased|
|Pulse||Normal||Thready||Faint or impalpable|
|* Best indicators of hydration status|
|Severity||Infants (weight < 10 kg)||Children (weight >10 kg)|
|Mild dehydration||5% or 50 mL/kg||3% or 30 mL/kg|
|Moderate dehydration||10% or 100 mL/kg||6% or 60 mL/kg|
|Severe dehydration||15% or 150 mL/kg||9% or 90 mL/kg|
|Solution||Carbohydrate (g/dL)||Sodium (mEq/L)||Potassium (mEq/L)||Base (mEq/L)||Osmolality|