Giant cell arteritis: suspicion and follow-up in the community

• Visual symptom, even transient (blurring, amaurosis, diplopia): urgent corticosteroid therapy and specialist opinion the same day, without waiting for results.

Laboratory tests (the same day)

• CRP
• FBCif neededInflammatory anaemia and thrombocytosis are seen in half of cases ^[1]; not essential for the diagnosis.
• Fibrinogen (if CRP normal or nearly so)if neededAt diagnosis, CRP alone is necessary; other markers of inflammation can be explored if it is normal or almost normal, fibrinogen rather than ESR ^[1].
• Rheumatoid factorif neededIf there are joint manifestations, the PNDS recommends these tests to rule out rheumatoid arthritis with a rhizomelic onset, more frequent in older people ^[1].
• Anti-CCP antibodiesif neededIf there are joint manifestations, the PNDS recommends these tests to rule out rheumatoid arthritis with a rhizomelic onset, more frequent in older people ^[1].
• ANCA (anti-MPO and anti-PR3), to be discussed with the specialistif neededThe PNDS recommends this test for the differential diagnosis (ANCA-associated vasculitis, which can affect the temporal artery) ^[1].
• Fasting plasma glucose and HbA1c, before corticosteroid therapy (if risk factor for diabetes)if neededThe PNDS recommends screening for diabetes before corticosteroids in people at risk (overweight, personal or family history of diabetes, gestational diabetes) ^[1].
• IGRA test (before corticosteroid therapy, depending on tuberculosis risk)if needednon-French guidelineEULAR (2022) suggests considering screening for latent tuberculosis before corticosteroid therapy, especially beyond 15 mg/day of prednisolone for more than 4 weeks ^[3]; the BSR (2020) asks to discuss exposure to tuberculosis and to screen for it according to national protocols ^[4]. The PNDS asks to discuss antituberculosis prophylaxis in case of recent contact, old untreated tuberculosis or a positive tuberculin test, without requesting routine testing ^[1]. IGRA is not reimbursed in France for this indication ^[5].

1 to 2 weeks after starting corticosteroids

• Serum potassium

At 1 month

• Venous plasma glucose, taken in late morning

Every month

• CRP
• Fibrinogen
• FBC (at each follow-up visit)if needednon-French guidelineThe BSR (2020) asks for at least an FBC with ESR or CRP at every follow-up visit, as platelets may be raised in giant cell arteritis ^[4]; the American Family Physician review (2022) also cites the FBC during follow-up ^[7]. In the PNDS, the FBC is part of the monitoring of tocilizumab and methotrexate ^[1].

Every 3 months (fasting)

• HbA1c
• Lipid profile