Which physical sign indicates dehydration in infants?

Dehydration in infants is indicated by specific physical signs, one of which is the presence of sunken or flat fontanelles. The fontanelles are the soft spots on an infant’s head where the skull bones have not yet fused together; they are filled with a membranous covering. When an infant becomes dehydrated, the body tends to pull fluids from less vital areas, which can cause the fontanelles to appear sunken.

Observing sunken fontanelles is a critical assessment finding for dehydration in this age group, as it reflects the loss of intracranial volume due to fluid depletion. Assessing fontanelles is a routine part of evaluating an infant's hydration status, making it an important sign for healthcare providers to recognize promptly. In contrast, other signs such as bright red cheeks, excessive sweating, or increased appetite do not specifically correlate with dehydration and may indicate different physiological states.