Antineutrophil Cytoplasmic Antibody-associated Vasculitis Complicating Graves' Disease: Report of Two Adult Cases

Two adult female patients with established Graves' disease were treated with propylthiouracil (PTU). One patient developed agranulocytosis, high fever of unknown origin and bilateral episcleritis. Another patient reported repeated attacks of common cold-like symptoms, polyarthralgia and skin purpura. There was no hematuria or proteinuria. Administration of PTU was withdrawn following identification of high myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) titer in the serum. Without steroids or immunosuppressive therapy, symptoms improved gradually in association with a fall in serum MPO-ANCA titer. We speculated that the symptoms of our two cases were due to MPO-ANCA associated vasculitis. MPO-ANCA positive vasculitis and glomerulonephritis are rare complications of PTU therapy, however, when these occur, the condition may become serious. Patients with Graves' disease treated with PTU should be carefully observed during therapy