From the Guidelines
For clinically evident temporal arteritis, the immediate diagnostic test recommended is a temporal artery biopsy, which should be performed as soon as possible but should not delay treatment initiation. This procedure involves removing a segment of the temporal artery for histopathological examination to identify inflammatory changes and giant cells characteristic of the disease 1.
Key Diagnostic Tests
- Temporal artery biopsy: removing a segment of the temporal artery for histopathological examination
- Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP): typically markedly elevated in temporal arteritis
- Complete blood count: may show normocytic anemia, and platelet count is often elevated
- Color duplex ultrasonography of the temporal arteries: non-invasive alternative or complement to biopsy, looking for the "halo sign" indicating vessel wall edema
- Magnetic resonance imaging (MRI) or computed tomography (CT) angiography: may be useful to evaluate the extent of vascular involvement, particularly in the aorta and its major branches
Recent Guideline Recommendations
According to the 2021 American College of Rheumatology/Vasculitis Foundation guideline for the management of giant cell arteritis and Takayasu arteritis, a temporal artery biopsy is recommended over temporal artery ultrasound for establishing a diagnosis of GCA 1. Additionally, the 2024 EULAR recommendations for the use of imaging in large vessel vasculitis in clinical practice suggest that ultrasound of temporal and axillary arteries should be considered as the first imaging modality to investigate mural inflammatory changes in patients with suspected GCA 1.
Prioritizing Treatment Initiation
It is essential to note that treatment with high-dose corticosteroids (typically prednisolone 40-60 mg daily) should be started immediately upon clinical suspicion to prevent vision loss, which can occur rapidly and be permanent if treatment is delayed 1.
From the Research
Immediate Diagnostic Tests for Temporal Arteritis
The following diagnostic tests are recommended for clinically evident temporal arteritis:
- Erythrocyte sedimentation rate (ESR) test: Although a raised ESR is commonly associated with temporal arteritis, a low ESR does not rule out the disease 2, 3, 4.
- C-reactive protein (CRP) test: CRP is positively correlated with ESR in untreated arteritis and may be more sensitive than ESR in following the adequacy of corticosteroid dosages 5.
- Temporal artery biopsy (TABx): The gold standard for diagnosis of temporal arteritis, which shows transmural inflammation, but a negative biopsy does not rule out the disease 3, 6.
Clinical Diagnosis
The diagnosis of temporal arteritis is clinical and should not be discarded by a negative TABx or normal laboratory findings 3, 6. Patients with classic clinical manifestations of temporal arteritis should be treated aggressively, even if the diagnostic tests are negative or inconclusive 3, 6.
Laboratory Findings
Laboratory findings such as elevated ESR and CRP can support the diagnosis of temporal arteritis, but normal findings do not rule out the disease 2, 3, 5, 4.