[A case of rapidly progressive glomerulonephritis exhibiting granulomatosis with polyangiitis (GPA) and extremely high level of PR3-ANCA with improvement of renal dysfunction after plasma exchange therapy].

A 68-year-old Japanese man was diagnosed with left otitis media with effusion and left uveitis more than 5 months before admission. He was urgently admitted to our hospital for progressive deterioration of his renal function [serum creatinine(Cr) 7.59 mg/dL] with proteinuria and urinary red blood cell casts, inflammation, and anemia. Additionally, his serum proteinase 3 antinuclear antibody (PR3-ANCA) level, determined by using the chemiluminescence enzyme immunoassay method, had increased to more than 3,500 U/mL. Hemodialysis (HD) was initiated on the third day after admission and renal biopsy was performed on the eighth day. The histological findings showed necrotic cellar crescents, hence, he was diagnosed as granulomatosis with polyangiitis on the basis of the clinical criteria. Methylprednisolone pulse therapy was administered from the 11th day. Thereafter, the administration of oral prednisolone (PSL) was started, and plasma exchange was initiated for the purpose of RP3-ANCA removal. In his clinical course, PSL was tapered as soon as possible because of the development of steroid psychosis, and we started intravenous cyclophosphamide on the 25th day instead of tapering the PSL. Subsequently, his renal function improved even without HD, and he was discharged on the 49th day. Although his PR3-ANCA level was still high after discharge, the administration of azathioprine led to a decrease in the PR-3 ANCA levels. About 2 years after discharge, the PR3-ANCA level decreased to 10.0 U/mL, and there has been no sign of GPA recurrence.