What symptom indicates severe dehydration beyond dry mouth?

A sunken fontanelle is a significant indicator of severe dehydration, especially in infants and young children. The fontanelle, or "soft spot," is an area on the top of a baby's head where the skull bones have not yet fused together. In cases of dehydration, the body loses fluids, and as a result, the soft spot can appear concave or sunken because there is not enough fluid to maintain the normal pressure and shape of the skull.

In infants, this physiological change is particularly important to assess because they can easily become severely dehydrated, and their ability to communicate their need for fluids is limited. Observing a sunken fontanelle in a pediatric patient can indicate a critical need for prompt medical intervention, often requiring rehydration either orally or intravenously.

Other symptoms listed, such as increased thirst and high fever, while suggestive of dehydration or illness, do not necessarily indicate the severity of dehydration like a sunken fontanelle does. Excessive tears typically suggest hydration rather than dehydration, demonstrating the importance of understanding these indicators in clinical assessments.