An older patient with diabetes is admitted with dehydration. Which finding would most strongly indicate dehydration is present?

• A. Dry mucous membranes and tachycardia
• B. Moist skin and normal heart rate
• C. Clear lungs and bradycardia
• D. Increased urine output

Answer: (A)

Dehydration reduces circulating blood volume, and the body responds by increasing heart rate to maintain perfusion. Dry mucous membranes reflect the loss of fluids in the extracellular space. Together, these signs—dry mucous membranes with tachycardia—most strongly indicate dehydration in an older patient with diabetes, where fluid loss is common due to osmotic diuresis. In contrast, moist skin with a normal heart rate suggests adequate hydration; clear lungs with bradycardia is not typical of dehydration, and increased urine output indicates the opposite of fluid deficit, since dehydration usually leads to concentrated urine and reduced urine output.