Which of the following is a characteristic sign of dehydration?

• A. Mild tachycardia
• B. Increased capillary refill time
• C. Prolonged jugular refill
• D. Obtunded mentation

Answer: (A)

When dehydration reduces the circulating blood volume, the body activates compensatory mechanisms to preserve perfusion to essential organs. The most consistent early signal is an increased heart rate as the autonomic system tries to maintain cardiac output despite lower preload. This mild tachycardia is a hallmark of volume loss and often appears before blood pressure drops, making it a characteristic sign of dehydration.

Increased capillary refill time can indicate reduced perfusion, but it’s less specific and can be influenced by temperature, age, and other factors. Prolonged jugular refill suggests higher venous pressure or congestion, not dehydration. Obtunded mentation points to more severe dehydration or CNS compromise and is not an early, common sign.