[Clinical features and outcomes of hyperthyroidism patients positive in propylthiouracil-induced antineutrophil cytoplasmic antibody]

Abstract

Objective: To analyze the clinical features and outcomes of hyperthyroidism patients positive in propylthiouracil (PTU)-induced antineutrophil cytoplasmic antibody (ANCA).

Methods: The clinical data, including the clinical manifestations, treatment, and outcomes of 45 PTU-induced ANCA positive patients with hyperthyroidism were prospectively studied.

Results: Seventeen of the 45 patients had clinically evident vasculitis and 28 of the 45 patients were not complicated by vasculitis. In the vasculitis group, 13 patients (76.5%) had renal involvement manifested by hematuria, proteinuria, and renal insufficiency. 7 of them (41.2%) had lung involvement and 6 of them had hemoptysis. Perinuclear ANCA (p-ANCA) was detected in all 17 patients and 16 of them (94.1%) were anti-myeloperoxidase antibodies (MPO-ANCA) positive. PTU was discontinued in all 17 patients and the treatment was switched over to methimazole (MMI) in 6 patients. Four patients with severe organ involvement received prednisone and immunosuppressant for 6 to 12 months. No relapse or death occurred during the follow-up period (8 to 60 months with a median of 30 months). All the 17 patients achieved clinical remission except for two that developed end stage renal disease due to late diagnosis. 27 of the 28 patients without vasculitis (96.4%) were p-ANCA positive and 14 of them (50.0%) were MPO-ANCA positive. PTU treatment was discontinued in 24 patients and switched over to MMI treatment in 15 patients, and 4 patients continued to take low dose PTU. No vasculitis manifestation occurred during the follow-up period (3 to 36 months with a median of 20 months). However, the ANCA titer declined slowly in most patients in both groups.

Conclusion: PTU treatment should be discontinued without delay in the PTU-induced ANCA positive patients with hyperthyroidism. Treatment can be switched over to MMI when necessary. Patients with severe organ involvement should receive prednisone and immunosuppressant. No vasculitis relapse is found during the follow-up after withdrawal of PTU. However, ANCA may keep positive for a long time.