C3 and granulomatosis with polyangiitis: Serological indicators of inflammation, including erythrocyte sedimentation rate and C-reactive protein levels, are frequently elevated in this disease, whereas C3 and C4 complement levels may be reduced.[3,7] Elevated c-ANCA levels are a highly helpful diagnostic tool for GPA.[8] In a meta-analysis, positive c-ANCA serology was 91% sensitive and 99% specific in GPA patients.[9] In our case, laboratory investigations revealed positive c-ANCA.