Clinical Practice Guidelines


  • See also:

    Guideline on Neonatal Fluid Requirements
    Guideline on intravenous fluid requirements
    Checklist of commonly used fluids
    Maintenance Fluid Calculator
    Hyponatraemia Guideline
    Hypernatraemia Guideline
    Gastroenteritis Guideline


    Dehydration can occur with many childhood illnesses. When assessing dehydration it is important to consider:

    Degree of dehydration (deficit)
    Maintenance fluid requirements
    Ongoing losses

    NOTE: If a child is haemodynamically unstable (ie shock) the shock needs to be corrected


    Give boluses of 10-20ml/kg of normal (0.9%) saline, which may be repeated.
    Do not include this fluid volume in any subsequent calculations of hydration

    RED FLAGS: Children with the following require Senior Medical Assessment

    • Short gut syndrome
    • Ileostomy
    • Complex/cyanotic congenital heart disease
    • Renal transplants or renal insufficiency
    • Very young ( <6 months)
    • Poor growth
    • Fortified feeds (concentrated feeds or caloric additives)
    • recent use of potentially hypertonic fluids (eg Lucozade)
    • other chronic diseases
    • repeated presentations for same/similar symptoms


    Assess on clinical signs and documented recent loss of weight (NB: Bare weight on same scales is most accurate). Weigh bare child and compare with any recent (within 2 weeks) weight recordings. Precise calculation of water deficit due to dehydration using clinical signs is usually inaccurate. The best method relies on the difference between the current body weight and the immediate pre-morbid weight. Unfortunately this is often not available.

    Clinical signs of dehydration give only an approximation of the deficit.

    Patients with mild ( <4%) dehydration have no clinical signs. They may have increased thirst.

    Moderate dehydration (4-6%)     Severe dehydration (>/= 7%)
    •  Delayed CRT
      (Central Capillary Refill Time) > 2 secs
    • Increased respiratory rate
    • Mild decreased tissue turgor
    • Very delayed CRT > 3 secs, mottled skin
    • Other signs of shock (tachycardia, irritable or reduced conscious level, hypotension)
    • Deep, acidotic breathing
    • Decreased tissue turgor

    Other 'signs of dehydration' (such as sunken eyes, lethargy & dry mucous membranes) may be considered in the assessment of dehydration, although their significance has not been validated in studies, and they are less reliable than the signs listed above.

    Unless an accurate & recent loss of weight is available as a guide, calculating percentage weight loss by clinical signs is only an estimation.

    A child's water deficit in mls can be calculated following an estimation of the degree of dehydration expressed as % of body weight. (e.g. a 10kg child who is 5% dehydrated has a water deficit of 500mls). The deficit is replaced over a time period that varies according to the child's condition. Precise calculations (eg 4.5%) are not necessary. The rate of rehydration should be adjusted with ongoing assessment of the child.

    Replacement of Deficit
    Replacement may be rapid in most cases of  gastroenteritis (best achieved by oral or nasogastric fluids), but should be slower in diabetic ketoacidosis and  meningitis, and much slower in states of  hypernatraemia (aim to rehydrate over 48 hours, the serum sodium should not fall by >1mmol/litre/hour).

    Ongoing losses (eg from drains, ileostomy, profuse diarrhoea)
    These are best measured and replaced - calculations may be based on each previous hour, or each 4 hour period depending on the situation. (eg. 200ml loss over previous 4 hours becomes replacement of 50ml/hr for the next 4 hours.)

    Replacement of Ongoing losses
    Normal (0.9%) saline may be sufficient, or 5% albumin may be used if sufficient protein is being lost to lower the serum albumin. See  Burns guideline for additional losses from burns.