Identify a common sign of dehydration in a patient.

Dry mucous membranes are a common sign of dehydration because the lack of adequate fluid intake can lead to reduced moisture in the body's tissues, including those in the mouth and nasal passages. When the body is dehydrated, it prioritizes maintaining essential functions and may conserve water by reducing the production of saliva and mucus, resulting in dryness. This is often observed as a clinical sign during a physical assessment of a patient.

In the context of dehydration, this sign can be a reliable indicator, along with other signs and symptoms. Other options may relate to fluid status but are not as directly indicative of dehydration as dry mucous membranes. For instance, high blood pressure is typically associated with fluid overload or other conditions but does not correlate with dehydration. Increased heart rate can occur in various states of hypovolemia but is a less specific indicator when considering hydration status alone. Frequent urination is more commonly associated with overhydration or conditions such as diabetes, rather than dehydration. Thus, observing dry mucous membranes is a straightforward and visible sign that clinicians often check during assessments for dehydration.