Which initial test is most helpful for a patient suspected of having temporal arteritis?

In the assessment of a patient suspected of having temporal arteritis, the erythrocyte sedimentation rate (ESR) is particularly useful as an initial test because it is a non-specific marker of inflammation. Temporal arteritis, also known as giant cell arteritis, is an inflammatory disease that primarily affects the large and medium-sized arteries, including the temporal arteries.

An elevated ESR indicates the presence of inflammation in the body, which supports the diagnosis of temporal arteritis, as the condition is characterized by systemic inflammation. High levels of ESR can prompt further investigation, including a temporal artery biopsy, which is a definitive diagnostic procedure for this condition.

In comparison, other tests listed do not provide direct insight into the presence of temporal arteritis. For example, a carotid ultrasound primarily evaluates blood flow and structure in the carotid arteries and would not be able to detect the specific inflammatory changes associated with temporal arteritis. A chest x-ray is helpful for analyzing thoracic structures but does not inform about cranial vascular inflammation. A complete blood count can indicate anemia or thrombocytosis, but it is less specific for inflammation compared to the ESR. Thus, while the complete blood count may provide some ancillary information, the ESR is the most pertinent initial investigation for confirming