Correspondence ANCA in Graves ’ Disease – Is it Anti-

T he article by M M Mehndiratta, et al,1 entitled “Carbimazole-induced ANCA positive vasculitis ” was informative.1 However, in this case during both episodes steroids have been used. Further, during the first episode the condition improved despite continuing the probable offending drug. Graves ’ disease itself is an autoimmune disease and autoantibodies other than thyroperoxidase antibodies are not totally unexpected. Though the study by Sera et al, did not find increased anti-MPO titres in untreated patients, studies that have found increased anti-MPO titres in untreated patients need to be mentioned. Gumà M, et al3 have found that 67 % of patients with Graves ’ hyperthyroidism show positive ANCA before medical treatment, which points to a relationship with the autoimmune disease itself. The detection of antineutrophil antibodies in Graves ’ disease with and without antithyroid medications is known for quite some time.4 Thyroid microsomal antigen (mostly thyroperoxidase) and human myeloperoxidase share 44 % amino acid sequence homology and cross-reactivity between thyroid microsomal antigen and human myeloperoxidase has been suggested to be an explanation of this phenomenon.5 However, later studies6,7 have discounted this possibility implying that truly elevated anti-MPO titre is present in untreated patients with Graves ’ hyperthyroidism