Table of Contents

HK J Paediatr (New Series)
Vol 10. No. 2, 2005

HK J Paediatr (New Series) 2005;10:162

Letter to the Editor

Letter to the Editor

DKK Ng, YY Lam, WF Lau

Dear Editor,

We read with interest the article "Use of intravenous therapy in the management of acute gastroenteritis in young children: a retrospective analysis" by Ip et al.1 We would like to point out that their comment of 'dehydration was based on the weight loss classification of <5% (mild), 5-10% (moderate) and >10% (severe)' requires clarification. As total body water and extracellular fluid volume as percentage of body weight decreases with increasing age (Table 1), a lesser decrease in body weight would result in similar clinical dehydration in older children.2 Hence, for children older than 1-year, a 3%, 6% and 10% weight loss correspond to mild, moderate and severe dehydration respectively.2,3 However, one should realise that the clinical features would not change much between 5% and 9% dehydration. Because of this threshold effect, distinguishing between mild and moderate dehydration on the basis of clinical signs alone might be difficult. Therefore, the updated recommendations group together patients with mild to moderate dehydration (Table 2). It is important for paediatricians to appreciate the differences as the accurate change in body weight is often not available and the rehydration regime would then be governed by the clinical assessment. In our experience in Kwong Wah Hospital, a significant proportion of children did not have an accurate body weight before the presenting episodes of gastroenteritis. This was further complicated by the fact that difference in the weighing scales used would also make interpretation of change in body weight difficult.

YY Lam
WF Lau

Department of Paediatrics
Kwong Wah Hospital

Table 1 Age related changes in percentage body weight of total body water, intracellular fluid and extracellular fluid2
 Total body waterExtracellular fluidIntracellular fluid
1-12 months653035
1-12 years602040
Adults 55-602035-40


Table 2 Assessment of dehydration*3
VariableNo or minimal, < 3%Mild-Moderate, 3-9%Severe, >= 0%
Blood pressure Normal Normal Normal to reduced
Quality of pulses Normal Normal or slightly decreasedModerately decreased
Heart rate Normal IncreasedIncreased+
Skin turgor Normal Decreased Decreased
Fontanelle Normal Sunken Sunken
Mucous membranesSlightly dry Dry Dry
Eyes NormalSunken orbitsDeeply sunken orbits
Extremities Warm, normal capillary refillDelayed capillary refillCool, mottled
Mental status NormalNormal to listlessNormal to lethargic or comatose
Urine outputSlightly decreased < 1 mL/kg/h<< 1 mL/kg/h
Thirst Slightly increasedModerately increasedVery thirsty or too lethargic to indicate

* If a clinician is unsure of the category into which a patient falls, it is recommended that therapy for the more severe category be used.
+ Bradycardia may appear in severe cases.


1. Ip KS, Ma YM, Chan JSH, Young BWY. Use of intravenous therapy in the management of acute gastroenteritis in young children: a retrospective analysis. HK J Paediatr (new series) 2005;10:10-4.

2. Greenbaum LA. Pathophysiology of body fluids and fluid therapy. In: Behrman RE, Kliegman RM, Jenson HB, Editors. Nelson textbook of pediatrics. 17th ed. Philadelphia: WB Saunders, 2004:191-252.

3. King CK, Glass R, Bresee JS, Duggan C; Centers for Disease Control and Prevention. Managing acute gastroenteritis among children: oral rehydration, maintenance, and nutritional therapy. MMWR Recomm Rep 2003;52(RR-16):1-16.


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