Final answer:
An elderly patient with normal WBCs and no fever might still be at risk of an infection if they exhibit an elevated heart rate, as this is an indicator of potential systemic infection or stress. so, option A is the correct asnwer.
Step-by-step explanation:
An elderly patient with normal white blood cells (WBCs) and no fever may still be at risk of an infection if other signs are present. Health professionals look beyond just WBC count and fever for indicators of infection. Signs that may warrant concern include elevated heart rate, which is a common physiological response to infection as the body attempts to increase blood flow and provide more immune cells to the site of infection.
Therefore, the correct answer to the question is that the clinician is worried about infection based on other signs, which could be an elevated heart rate (A). This elevated heart rate, particularly if it's tachycardia (a heart rate over 100 beats per minute), could signify the body's response to systemic infection or other stressors.
It's also important to note that in an immunocompromised individual, like the patient Benjamin described in the case study, typical signs of infection such as a high WBC count may not always be present, thus it is crucial to assess other clinical features when infection is suspected.