Prevalence of perinuclear antineutrophil cytoplasmic antibody in patients with Graves' disease treated with propylthiouracil or methimazole in Taiwan.

BACKGROUND AND PURPOSE: Antineutrophil cytoplasmic antibody (ANCA)-mediated vasculitis can be induced by propylthiouracil (PTU) and methimazole (MMI) for the treatment of Graves' disease. This study investigated the prevalence of ANCA positivity and its clinical correlates in Taiwanese patients with Graves' disease treated with PTU or MMI.

METHODS: Eighty nine patients with Graves' disease who were currently being treated with PTU (n = 47) or MMI (n = 42) were included in the study. Sera were screened for ANCA by indirect immunofluorescence. The antigenic specificity of myeloperoxidase or proteinase-3 was measured by enzyme-linked immunosorbent assay. Thyroid autoantibodies against microsomal antibodies (AMA) and thyroglobulin antibodies were detected by indirect passive hemagglutination assays, and thyroid autoantibodies against thyrotropin receptor were detected by a radioreceptor assay. The correlations among ANCAs, clinical manifestations, gender, duration of treatment, and thyroid autoantibodies were analyzed by logistic regression.

RESULTS: 20.2% of patients with Graves' disease receiving PTU and MMI were seropositive for ANCA; all of them were perinuclear-ANCA (p-ANCA)-positive. The frequency of p-ANCA-positive status in the PTU treatment group was significantly higher than in the MMI treatment group (31.9% vs 7.1%; p = 0.01). The mean duration of PTU treatment was 25 +/- 16 months, and was 30 +/- 21 months for the MMI treatment. In the PTU treatment group, the average duration of treatment in p-ANCA-positive patients was significantly longer than in p-ANCA negative patients (32.9 +/- 16.3 vs 19.6 +/- 12.1 months, p = 0.04). In addition, the prevalence of AMA positivity was significantly lower in p-ANCA-positive patients than in p-ANCA negative patients (53.3% vs 90.6%; p = 0.01).

CONCLUSIONS: Only p-ANCA positivity was found in long-term treatment with PTU and MMI in Graves' disease. A higher frequency of p-ANCA positivity was found in the PTU treatment group than in the MMI treatment group. However, the presence of AMA was less frequent in p-ANCA-positive patients compared to p-ANCA-negative patients treated with PTU.