Endocrine Abstracts

We report the cases of two identical twins with Graves’ disease which proved very difficult to control and followed very similar stormy course. Twin A was a 20 years old female of 12 weeks gestation when she was referred to endocrine clinic with history of weight loss, palpitations and tremor. Her thyroid function tests revealed TSH <0.08 mU/L (0.03–4.30), FT4 82.5 pmol/L (12–22 pmol/L) and FT3 44.4 pmol/L (2.8–7.1) with positive thyroid receptor antibody. Twin B presented when she was aged 21 years with similar complaints. Her Thyroid Function Tests revealed TSH <0.08 mU/L (0.03–4.40), FT4 73.7 pmol/L (12–22), and FT3 38.4 pmol/L (2.8–7.1) On clinical examination they both had evidence of small goitre, tremor and tachycardia with significant thyroid eye disease. Due to the severity of their disease it was difficult to treat them medically as they did not respond to the maximal doses of antithyroid drugs. Therefore Twin A was referred for subtotal thyroidectomy as she was at risk of thyroid storm precipitated by radioablation in view of incomplete response to high dose antithyroid drugs while Twin B is currently being prepared for radioablation under steroid cover provided good thyroid control can be obtained. This is a rare presentation of identical twins presenting at around the same age with marked thyrotoxicosis and ophthalmic involvement in both siblings. Their disease course and severity was almost identical. This could be a serendipity, but raises the issue of the need for screening for thyroid disorders in siblings of those with known thyroid disease, particularly females and more so in identical twins. It also raises the interesting possibility that disease course and severity may have significant genetic determinants.