Which laboratory test is most commonly elevated in patients with GCA?

The most commonly elevated laboratory test in patients with Giant Cell Arteritis (GCA) is C-reactive protein. GCA is a form of vasculitis that primarily affects the medium and large arteries, particularly in the head and neck. The condition is characterized by inflammation that can lead to serious complications if not promptly diagnosed and treated.

C-reactive protein is a substance produced by the liver in response to inflammation. Elevated levels of C-reactive protein are indicative of an inflammatory process occurring in the body, making it a valuable marker for conditions like GCA. Patients with GCA frequently present with systemic symptoms such as fever, fatigue, and malaise, which are associated with increased levels of inflammatory markers, including C-reactive protein. Therefore, measuring this protein is crucial in supporting the diagnosis of GCA and monitoring disease activity.

In contrast, while a Complete Blood Count can provide useful information, it is not as directly linked to the inflammatory process specific to GCA as C-reactive protein is. Antinuclear Antibody tests are more relevant in autoimmune conditions such as lupus and do not have a direct association with GCA. A urinalysis is often employed to assess kidney function and to look for signs of systemic diseases but does not typically