Endocrine Abstracts

The most frequent side effects of antithyroid drugs are skin reactions (6%), gastrointestinal effects (5%) and arthralgia (5%). Other complications such as antithyroid arthritis syndrome (1%), agranulocytosis (0.5%) and hepatitis (0.2%) occur rarely.

We describe the case of a 20-year-old woman with Graves’ disease. Two weeks after the beginning of carbimazole therapy, she developed an urticarial reaction that led to discontinuation of treatment. Nevertheless, diffuse aching limbs appeared abruptly later on. Due to the lack of clinical improvement, our patient was admitted to the hospital. She had skin reaction with itching, skin rash, dermatographic urticaria, and arthralgia involving her left knee and right shoulder. Treatment with antihistamin drugs and analgesics has been started but arthralgia progressed to migratory oligoarthritis and body temperature increased to 38°C. Blood tests only showed inflammatory syndrome. Creatine kinase level, joint X rays, left knee joint viral serologies, ANCA antibodies, rheumatoid factor, anti-nuclear antibodies, anti CCP antibodies and anti SSA/RO antibodies were normal. The patient was treated with anti-histamin and non-steroidal anti-inflammatory drugs as well as corticosteroids and clinical improvement occurred a few weeks later with no recurrence of skin rash or arthralgia. Hyperthyroidism was treated with 131 iodine.

Polyarthritis is a rare major side effect of antithyroid drugs. It is important to distinguish anti thyroid arthritis syndrome from minor arthralgia. Contrary to minor arthralgia, anti thyroid arthritis syndrome requires treatment discontinuation, due to cross reactions between the different medications. The majority of polyarthritis cases due to antithyroid treatment described in the literature appear in an autoimmune context. Here we described a rare case of antithyroid arthritis syndrome without evidence of autoimmunity.