Clinical Assessment of Dehydration

Clinical assessment of dehydration is always approximate, and the child should be frequently re-evaluated for continuing improvement during correction of dehydration.

Mild Moderate Severe
Weight loss for infants Up to 5% 6-10% 10-15%

Weight loss for children

Up to 3%

6%

9%
Appearance Active, alert Irritable, alert, thirsty Lethargic, looks sick
Capillary filling (compared to your own) Normal Slightly delayed Delayed
Pulse Normal Fast, low volume Very fast, thready
Respiration Normal Fast Fast and deep
Blood pressure Normal Normal or low Orthostatic hypotension Very low
Mucous memb. Moist Dry Parched
Tears Present Less than expected Absent
Eyes Normal Normal Sunken
Pinched skin Springs back Tents briefly Prolonged tenting
Fontanel (infant sitting) Normal Sunken slightly Sunken significantly
Urine flow Normal Reduced Severely reduced

When we talk of "5% dehydration", it means that the child has lost an amount of fluid equal to 5% of the body weight. If you have an accurate pre-illness weight, you may use that weight. Alternatively, the pre-illness weight can be calculated as follows:

So,

  • A 10 kg child who is 5% dehydrated will weigh 9.5 kg.
  • A 10 kg child who is 10% dehydrated will weigh 9 kg.
  • A 5 kg child who is 10% dehydrated will weigh 4.5 kg.

The child's current (dehydrated) weight can be used for calculation of dehydration and maintenance fluids. After all, clinical assessment of dehydration, and therefore the volume needed for correction, is approximate!