In a 60-year-old man with severe retro-orbital headache, temporal artery tenderness, an unremarkable neurological exam, and CT showing only mild microangiopathic changes, what additional workup is indicated?

Giant Cell Arteritis Workup

Immediate Laboratory Testing Required

This patient requires immediate ESR and CRP measurement followed by urgent high-dose corticosteroid initiation without waiting for results, as the combination of severe retro-orbital headache and temporal artery pain in a 60-year-old man represents giant cell arteritis (GCA) until proven otherwise. 1

Essential Immediate Labs

• Draw ESR and CRP immediately before any other testing, as ESR >50 mm/h has 78.9% sensitivity for GCA and CRP elevation has 79.2% sensitivity 1
• Do not delay treatment while awaiting these results—the priority is preventing irreversible bilateral blindness 1, 2
• ESR >60 mm/h significantly upgrades suspicion for GCA, and ESR >100 mm/h has 92.2% specificity with a positive likelihood ratio of 3.11 1, 3

Critical Clinical Assessment Details

Beyond the temporal artery tenderness already noted, specifically assess for:

• Jaw claudication (pain with chewing)—this is pathognomonic for GCA with a positive likelihood ratio of 4.90 and present in approximately 50% of cases 1, 4
• Visual symptoms including transient vision loss, diplopia, or any acute vision changes—these indicate ischemic optic neuropathy representing an ophthalmologic emergency 5, 1
• Constitutional symptoms including low-grade fever, weight loss, malaise, and proximal myalgia (polymyalgia rheumatica symptoms) 5, 1, 4
• Scalp tenderness beyond the temporal area, which has 38.9% sensitivity and 78.9% specificity for GCA 1

Immediate Management Algorithm

Step 1: Initiate Corticosteroids Immediately

• Start prednisone 40-60 mg daily immediately upon clinical suspicion, even before laboratory confirmation 1, 2, 4
• This is the single most important intervention to prevent permanent bilateral blindness 1
• Delaying corticosteroids while awaiting ESR/CRP results or temporal artery biopsy is the most common and dangerous error 1, 2

Step 2: Arrange Temporal Artery Biopsy

• Schedule temporal artery biopsy urgently (ideally within 1-2 weeks), but do not delay treatment 1, 2, 4
• The biopsy remains diagnostic for up to 2 weeks after corticosteroid initiation without affecting diagnostic yield 1, 2, 4
• Temporal artery biopsy is the gold standard with 67-97% sensitivity 1, 6

Step 3: Ophthalmology Referral

• Obtain same-day or next-day ophthalmology consultation to assess for visual symptoms or subclinical involvement 2
• This facilitates temporal artery biopsy planning and ongoing management 1

Step 4: Stroke Center Referral if Indicated

• If there are any visual symptoms suggesting retinal or ophthalmic artery occlusion, refer immediately to the nearest stroke center for neurological evaluation 5
• Up to 24% of patients with central retinal artery occlusion have concurrent cerebrovascular accident on diffusion-weighted MRI 5

Additional Diagnostic Considerations

Complete Blood Count

• Assess for anemia, thrombocytosis, and leukocytosis, which commonly accompany GCA 1, 6

ANCA Testing in Atypical Cases

• If the patient has atypical manifestations (ear/nose/throat involvement, renal/pulmonary/neurologic symptoms), is refractory to glucocorticoid treatment, or experiences early relapse, consider ANCA testing 7
• ANCA-associated vasculitides can present with temporal arteritis in 66% of cases with atypical GCA features 7
• Patients with temporal arteritis revealing AAV are younger (median age 70 vs 74 years), more frequently male, and have higher CRP levels 7

Imaging for Large Vessel Involvement

• Consider PET/CT or vascular imaging to identify extracranial large vessel involvement, as 86% of GCA patients show uptake consistent with large vessel vasculitis 2, 8
• Check peripheral pulses and blood pressure in both arms 2

Critical Pitfalls to Avoid

• Never delay corticosteroids while awaiting ESR/CRP results or temporal artery biopsy in suspected GCA with headache and temporal artery tenderness 1, 2
• Do not attribute symptoms to migraine in a 60-year-old with new-onset headache—new-onset persistent localized headache after age 50 warrants GCA evaluation 1
• Do not pursue neuroimaging first when GCA is suspected based on classic symptoms (the CT already performed showing only microangiopathic changes does not exclude GCA) 1
• Do not wait for biopsy confirmation before starting treatment—vision loss is irreversible once established 1, 2, 6
• Approximately 11% of GCA patients have normal inflammatory markers, so clinical suspicion overrides laboratory values 1

Monitoring Strategy

• Monitor ESR and CRP every 2-4 weeks initially until normalization, then every 6 months during maintenance therapy 1, 2
• Most patients require 2-3 years of treatment with gradual tapering guided by clinical symptoms and inflammatory markers 2, 4
• 34-62% of patients experience flares during taper, requiring close monitoring 1