[Case of ANCA-associated glomerulonephritis detected at an early phase].

A 71-year-old man was admitted with low-grade fever, a high titer of CRP and ANCA. He was diagnosed as MPO-ANCA-associated vasculitis. On admission, his renal function was normal. Proteinuria and extra renal symptoms were not recognized. Only hematuria and hyaline cast were detected. A high titer of CRP and MPO-ANCA persisted. After obtaining informed consent, a renal biopsy was performed, revealing cellular crescentic glomerulonephritis and necrotizing vasculitis. The findings of the renal biopsy indicated an early phase of ANCA-associated nephritis. After MPSL pulse therapy, renal function was in the nomal range and proteinuria and hematuria disappeared. This present case demonstrated that early diagnosis and treatment are very important to sustain normal renal function if a high titer of MPO-ANCA is recognized in an elderly person without proteinuria.