Human T-lymphotropic virus type I-associated uveitis in patients with Graves' disease treated with methylmercaptoimidazole.

Human T-lymphotropic virus type I (HTLV-I) is responsible for a certain form of uveitis [HTLV-I-associated uveitis (HAU)]. A previous history of Graves' disease has been reported in 9-17% of the patients with HAU. In this study, the prevalence of patients with either HTLV-I antibody or uveitis was evaluated in 819 consecutive patients with thyroid disorders between 1991 and 1992. Serum HTLV-I antibody was found in 25 of 392 patients with Graves' disease, 19 of 257 with chronic thyroiditis, and 3 of 170 with nodular goiter. Five of 25 HTLV-I-positive patients with Graves' disease developed HAU. All of these 5 patients had been treated with methylmercaptoimidazole (MMI). Within a few months before the onset of uveitis, 3 patients were hyperthyroid, and 2 were hypothyroid. In 2 of 5 patients, an exacerbation of uveitis occurred soon after the readministration of MMI for the relapse of hyperthyroidism. None of the 367 HTLV-I negative patients with Graves' disease nor 22 HTLV-I-positive patients with chronic thyroiditis or nodular goiter developed uveitis. It was therefore suggested that Graves' disease, thyroid dysfunction and/or MMI administration might be related to the development of HAU.