Endocrine Abstracts

Carbimazole is one of the most commonly prescribed endocrine medications. There are a wide range of side effects associated including bone marrow disorders, severe cutaneous reactions, agranulocytosis and vasculitis. There have been few reports of anti-thyroid associated arthritis, described as migratory arthritis with prompt resolution following medication discontinuation. Side effects reported in British national Formulary and Electronic Medicine Compendium include myopathy but not inflammatory arthritis. We present a case of 56-year-old lady found to have Graves’ thyrotoxicosis with background of eosinophilic asthma, primary biliary cirrhosis and Sjogren’s syndrome. After starting 20 mg carbimazole she complained of swollen and painful joints spreading between different locations, muscle aches and dark urine with worsening mobility. Investigations demonstrated ESR 119, CRP 126, TSH receptor antibody 4.2, TSH <0.01, T4 30.9 pmo/l, T3 12.4 pmo/l, ANA/ANCA/ENA negative. Carbimazole was stopped by the patient with rapid resolution of symptoms. Inflammatory markers subsequently normalized. She was given low dose of propylthiouracil which was tolerated well and opted for early radioactive iodine treatment in view of underlying liver disease and concern about side effects.

Conclusion: It is important to recognize migratory arthritis as a potential side effect and differentiate from vasculitis which can manifest similarly. This case demonstrates the investigations required in differential diagnosis of these symptoms and highlights the improvement seen with drug withdrawal. Patients with thyroid disease often experience a multitude of symptoms and it is important for physicians to be able to recognize those that may relate to therapy rather than underlying disease.