However, testing for rheumatic diseases or vasculitis using specific antibodies, such as antinuclear antibodies (ANAs), rheumatoid factor (RF), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), anti-citrullinated peptide antibody (ACPA), anti-neutrophil cytoplasmic antibody (ANCA), and anti-glomerular basement membrane (anti-GBM) antibodies, may be helpful in some cases. Here, CRP is linked to vasculitis.