What laboratory parameter would best indicate a potential infection in a patient?

An elevated white blood cell (WBC) count is widely recognized as a significant indicator of infection in a patient. When the body is confronted with an infection, whether bacterial, viral, or fungal, the immune system responds by increasing the production of white blood cells, which are crucial for fighting off pathogens. This response often leads to a noticeable elevation in the WBC count, reflecting the body's efforts to combat the infection.

In clinical practice, a WBC count above the normal range can prompt further investigation to determine the underlying cause, including potential infections. The specific type of infection may also be further assessed by examining the differential count of the white blood cells, which can indicate whether the infection is likely to be viral or bacterial based on the predominant cell types present.

Other parameters mentioned, such as a low platelet count, decreased lymphocyte percentage, or a normal hematocrit, do not directly correlate to the presence of infection. While they may have their clinical significance, they do not serve as reliable indicators for diagnosing an active infection. Thus, an elevated WBC count remains the best laboratory parameter to suggest a potential infectious process in a patient.