Which is a sign of severe dehydration in a pediatric patient?

Lethargy and dry mucous membranes are key indicators of severe dehydration in pediatric patients. When a child is severely dehydrated, the body loses significant amounts of water and electrolytes, leading to a noticeable decrease in energy levels, resulting in lethargy. Dry mucous membranes occur because there is insufficient fluid in the body to keep the tissues hydrated, affecting the mouth, nasal passages, and skin.

In contrast, increased urination is generally a sign of hydration or a response to fluid intake, and clear skin and normal activity levels indicate proper hydration and health. Therefore, the presence of lethargy and dry mucous membranes reflects a critical condition where the body's fluids are dangerously low, warranting immediate medical attention.