What is a key indicator of infection in a patient?

An elevated white blood cell count is a key indicator of infection because it typically signifies that the body is responding to a pathogenic threat. White blood cells, or leukocytes, play a crucial role in the immune response by identifying and fighting infections. When an infection occurs, the bone marrow increases the production of white blood cells to help combat the invading microorganisms.

Infections often result in the presence of neutrophils, which are a type of white blood cell that respond quickly to infection. The elevated count, often categorized as leukocytosis, can assist healthcare providers in diagnosing and determining the severity of the infection, guiding treatment options.

In contrast, elevated blood pressure may not necessarily indicate infection and could be influenced by a variety of other factors, such as pain or anxiety. A normal heart rate also does not provide specific information about infection status, as it can remain within the normal range in many conditions, including infections. Lastly, a normal white blood cell count typically suggests that there may not be an active infection or that the body's immune response is not being challenged. Thus, elevated white blood cell count stands out as the most significant indicator of infection among the choices provided.