During a fever, what vital sign is typically elevated?

The most pertinent vital sign that is typically elevated during a fever is body temperature. Fever is defined as an increase in the body’s core temperature, typically above 100.4°F (38°C). This physiological response is primarily driven by the hypothalamus, which raises the set point for body temperature in response to infection, inflammation, or other illnesses.

During a fever, the body’s defenses work to combat pathogens, and the higher temperature can help enhance the efficacy of the immune response. As the body tries to reach this new set point, it may generate heat through increased metabolism, shivering, and other mechanisms, resulting in an elevated body temperature.

While it is true that other vital signs, such as heart rate, blood pressure, and respiratory rate, can also show changes during fever, their increases are generally secondary effects rather than the primary change. For instance, elevated heart rate often occurs as a compensatory response to increased body temperature, but body temperature remains the primary indicator of fever itself. This distinction underscores the importance of recognizing body temperature as the vital sign that directly reflects the presence of a fever.