Occurrence of antineutrophil cytoplasmic antibodies and associated vasculitis in patients with hyperthyroidism treated with antithyroid drugs: A long-term followup study

Abstract

Objective: To test whether antineutrophil cytoplasmic antibodies (ANCA) and ANCA-associated vasculitis (AAV) are not only induced during treatment with antithyroid drugs, but can also become evident when medication has been ceased, possibly after years.

Methods: Patients who visited our hospital for the treatment of hyperthyroidism were included (n = 207). Treatment consisted of antithyroid medications, radioactive iodide, thyroidectomy, or a combination of these treatment options. Patients were retested 3-6 years later to evaluate long-term effects of antithyroid drugs. Patients were tested for the presence of ANCA and, if positive, evaluated for the presence of AAV.

Results: Of 209 patients with hyperthyroidism, 12 patients (6%) were positive for myeloperoxidase- (MPO-), proteinase 3-, or human leukocyte elastase-ANCA. Seventy-seven of 209 patients were retested; 1 patient who had not been treated with antithyroid drugs had developed MPO-ANCA. In 3 of 6 patients previously positive, ANCA could still be detected. The presence of ANCA was highly associated with treatment with antithyroid drugs (odds ratio 11.8 [95% confidence interval 1.5-93.3]). Of 13 patients with a positive ANCA result on enzyme-linked immunosorbent assay, AAV with glomerulonephritis was diagnosed in 4 (31%).

Conclusion: The presence of ANCA with or without vasculitis is associated with previous treatment with antithyroid drugs, possibly after years.