Threatened (eg, vision change) or confirmed vision loss in GCA requires high-dose intravenous glucocorticoids (eg, methylprednisolone 500-1,000 mg daily), followed by oral therapy with a slow taper over several months to prevent worsening or contralateral vision loss.  Temporal artery biopsy can confirm the diagnosis of GCA; however, therapy should be started immediately when the diagnosis is suspected and should not be withheld while awaiting confirmation. UWorld qid: 3164

Giant cell arteritis. These people have inflammation of large and medium vessels, we think carotid arteries mostly, and their branches. The most immedieate concern for these patients is BLINDNESS which can be caused if the retinal artery gets blocked (branch of internal carotid). SO for these people you don't wait for a biopsy you start them on high dose steroids ASAP. mc in >50 white women. But sometimes they like to get interesting with the demographics.

• Presentation most consistent with temporal arteritis (older patient with headache, jaw claudication, elevated ESR and tender, enlarge temporal arteries)
• Key idea: Because of risk for blindness and imperfect sensitivity of temporal artery biopsy (because disease only affects section of temporal artery so biopsy may miss affected segment), patients with suspected temporal arteritis should begin empiric treatment with corticosteroids BEFORE temporal artery biopsy is performed

Think of it as spectrum PMR >> GCA >> GCA with Vision loss

In PMR you treat with low dose steroid only. If improve great. No need for a biopsy.

Temporal artery biopsy is indicated only in GCA with or without PMR.

But when things get dark you don;t wait for a biopsy and start pulse dose steroids.