A case of membranous nephropathy with ANCA-associated necrotizing glomerulonephritis during oral administration of PTU for Graves' disease

We experienced a coincidental case of two types of glomerulopathy associated with Graves' disease. A 64-year-old man, who had been treated with propylthiouracil(PTU) for Graves' disease for 15 years, was admitted to our hospital for macroscopic hematuria and rapidly progressive deterioration of renal function. Although his thyroid function had been within the normal range during treatment, the level of thyrotropin receptor antibody(TRAb) gradually increased from a year before admission. Serological tests revealed that he was positive for myeloperoxidase-antineutrophil cytoplasmic antibody(MPO-ANCA). The renal biopsy specimen showed necrotizing and crescentic glomerulonephritis(GN) superimposed on membranous nephropathy(MN). This is a rare case of MN complicated with ANCA associated crescentic GN in a Graves' disease patient. Association of these two renal alterations was not clearly defined. MN involved with Graves' disease also has been rarely reported. Some reports demonstrated deposition of thyroglobulin and other thyroid related antigens in the glomeruli. In the present case, long-term impairment of Graves' disease and elevation of TRAb might have been responsible for the formation and deposition of thyroid-associated immune complex in the glomeruli. As for crescentic GN, PTU might have induced ANCA-associated GN independently of MN. This case is instructive for considering the relation between Graves' disease and renal injury.