From the Guidelines
The workup for Giant Cell (Temporal) Arteritis should include a thorough clinical evaluation, laboratory tests, and a temporal artery biopsy, with initiation of high-dose prednisone (40-60mg daily) immediately if clinical suspicion is high, even before biopsy results, to prevent vision loss. This approach is supported by the 2021 American College of Rheumatology/Vasculitis Foundation guideline for the management of giant cell arteritis and takayasu arteritis 1. The guideline conditionally recommends an initial unilateral temporal artery biopsy over bilateral biopsies, a long-segment temporal artery biopsy specimen (>1 cm) over a short-segment temporal artery biopsy specimen (<1 cm), and obtaining a temporal artery biopsy specimen within 2 weeks of starting oral glucocorticoids (GCs) over waiting longer than 2 weeks for a biopsy.
Key components of the workup include:
- Laboratory tests such as ESR and CRP, which are typically elevated in temporal arteritis
- A complete blood count, which often shows normocytic anemia
- Liver function tests, which may show mildly elevated alkaline phosphatase
- Temporal artery biopsy, which should be performed within 1-2 weeks of starting steroids
- Consideration of additional imaging such as MRI, CT angiography, or PET scan if large-vessel involvement is suspected
The 2021 guideline also conditionally recommends temporal artery biopsy over temporal artery ultrasound and MRI of the cranial arteries for establishing a diagnosis of GCA 1. For patients with suspected GCA and a negative temporal artery biopsy result, noninvasive vascular imaging of the large vessels with clinical assessment is recommended to aid in diagnosis 1.
After diagnosis, prednisone is typically continued at high doses for 2-4 weeks, then gradually tapered over months, with consideration of steroid-sparing agents like methotrexate or tocilizumab for patients requiring long-term therapy 1. Regular follow-up with ESR/CRP monitoring helps guide therapy adjustments.
It is essential to prioritize the prevention of vision loss and other complications associated with Giant Cell Arteritis, and the recommended approach is based on the most recent and highest-quality evidence available 1.
From the Research
Diagnosis of Giant Cell Arteritis
The diagnosis of Giant Cell Arteritis (GCA) is primarily clinical, with laboratory tests and temporal artery biopsy (TAB) used to support the diagnosis 2, 3.
- Clinical presentation: new-onset headache, jaw claudication, proximal myalgia, weight loss, and fever may lead to the diagnosis 3.
- Laboratory values: erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), fibrinogen, thrombocytes, and cardiolipin antibodies may indicate GCA, but none of these prove the diagnosis 3.
- Temporal artery biopsy: the gold standard for diagnosis of GCA, but a negative result does not exclude the diagnosis due to skip lesions 2, 3.
Temporal Artery Biopsy
Temporal artery biopsy is suggested to be performed within 2 weeks from the initiation of corticosteroids 4.
- The duration of corticosteroid treatment may affect the positivity of TAB, with a more than 7 days' duration of steroid treatment linked with lower rates of positive TAB 4.
- The positivity rate of temporal artery biopsy was found to be 23.7% in one study, with significant associations between jaw claudication, high initial clinical suspicion of disease, and specimen positivity 5.
Treatment
Patients with suspected GCA should be started on high-dose corticosteroid therapy without delay, with a temporal artery biopsy performed after initiation of therapy to confirm the diagnosis 6.
- Treatment may begin with high-dose oral prednisone in patients without visual or neurologic symptoms, or with intravenous methylprednisolone sodium succinate for patients with acute visual or neurologic symptoms 6.
- The treatment regimen should include calcium, vitamin D, and peptic ulcer prophylaxis, as indicated, and should be tapered and modified according to ESR, CRP, and signs and symptoms of GCA 6.