Dehydration, Fluid & Electrolyte Balance & Fever in Children

Infants and young children are more vulnerable to dehydration than adults because a larger proportion of their body weight is water, their fluid reserves are smaller, and losses from vomiting, diarrhea, or fever proportionally represent a bigger deficit — dehydration is typically classified as mild, moderate, or severe based on findings like capillary refill time, skin turgor, mucous membrane moisture, tear production, urine output, and mental status. Warning signs of worsening or severe dehydration include a sunken fontanelle in an infant, delayed capillary refill (over 2 seconds), decreased or absent urine output (a caregiver reporting significantly fewer wet diapers than usual is a meaningful clinical clue), lethargy, and, in infants, a weak or absent cry with few or no tears when crying. Oral rehydration solution is preferred for mild-to-moderate dehydration when the child is able to tolerate oral intake; IV fluids are reserved for moderate-to-severe dehydration, inability to tolerate oral intake, or ongoing significant losses.