Propylthiouracil associated antineutrophil cytoplasmic antibodies (ANCA) in patients with childhood onset Graves' disease.

Propylthiouracil (PTU) can induce anti-myeloperoxidase (MPO-ANCA) positive vasculitis. We performed a cross-sectional study to estimate the prevalence of MPO-ANCA in patients with childhood onset Graves' disease (GD) receiving PTU and to assess the relationship between ANCA and clinical manifestations of vasculitis. We studied 60 patients (59 girls and one boy) between 7.3 and 25.0 years of age (mean +/- SD, 14.71 +/- 4.49). GD, diagnosed at the age of 3.0 to 14.5 years (11.3 +/- 2.48), was designated as: newly diagnosed, on PTU therapy, and after PTU discontinuation in 4, 50 and 6 patients, respectively. Manifestations of vasculitis were noted and the patients were tested for MPO-ANCA, antinuclear antibodies, blood urea nitrogen, creatinine and urine analysis. Twenty-six patients (43.3%) reacted positively for MPO-ANCA, 23 were on PTU therapy (0.42 to 6.00, median 3.00 years) and three had discontinued PTU. There were 34 (56.7%) ANCA-negative patients and 27 patients on PTU therapy (0.25 to 5.17, median 1.00 years, p = 0.012). Vasculitis presented in 16 patients (26.7%), all of whom were receiving PTU at the time of the study. The percentage of vasculitis among MPO-ANCA positive patients was 27.6% more than in the negative group, p = 0.017. PTU was discontinued in patients with vasculitis and positive for MPO-ANCA. Our findings show a high prevalence of MPO-ANCA positivity and a significantly higher percentage of vasculitis among these patients, suggesting that patients taking PTU should be closely observed for the appearance of MPO-ANCA and signs of vasculitis, especially patients GD who have been treated for a long time.