A successful pregnancy and delivery case of Graves' disease with myeloperoxidase antineutrophil cytoplasmic antibody induced by propylthiouracil.

A 30-year-old female patient, diagnosed as having Graves' disease in 1996, was treated with propylthiouracil (PTU) for 4 years. She developed a low-grade fever from December 1999. As myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) vasculitis is one of the adverse effects of PTU, we examined serum MPO-ANCA level and found it was positive, but cytoplasmic-ANCA (c-ANCA) was negative. There were no symptoms that indicated other diseases associated with MPO-ANCA. She was confirmed to be at 6 weeks gestation, and thyroid hormone levels were elevated at that time. We discontinued PTU and gave methyl-mercaptoimidazole (MMI), and the titer of MPO-ANCA fell along with fever. Therefore we estimated the case as probable MPO-ANCA positive vasculitis induced by PTU. MMI was also suspended because of the development of hepatic dysfunction. After thyroid function was normalized by administration of potassium iodide, she underwent subtotal thyroidectomy, and delivered a 2350 g infant at 38 weeks' gestation, which was less than the normal birth weight of 2400 g. MPO-ANCA is considered to be one reason of low birth weight infant including hyperthyroidism. It is necessary to consider the appearance of the possibility of MPO-ANCA positive vasculitis in patients who are treated with PTU.