The study objective was the characterization of CRP levels in idiopathic (iSGS) and GPA-SGS to assess CRP's ability to distinguish SGS subtypes and predict SGS progression and recurrence.<h4>Methods</h4>Retrospective review of patients with idiopathic or GPA-SGS from 2007 to 2024 at a single institution. The gene discussed is CRP; the disease is granulomatosis with polyangiitis.