HMGB1 and anti-neutrophil cytoplasmic antibody-associated vasculitis: Urinary HMGB1 levels in AAV patients in active stage were significantly higher than those in AAV patients in remission and healthy controls (1.46 [0.56-3.43] versus 0.38 [0.10-1.35] mg/μmolCr, P=0.001; 1.46 [0.56-3.43] versus 0.48 [0.40-0.60] mg/μmolCr, P=0.000, respectively).