A rare case of thyroid eye disease
R Agha-Jaffar, M Sira, M Kostoula, J Cox, S Robinson, St Mary’s Hospital.
Resistance to thyroid hormone (RTH) is a rare inherited syndrome caused by mutations in the genes encoding for the thyroid hormone receptor. Recent evidence suggests that there is an association between RTH and autoimmune thyroid disease (AITD), with an increased odds ratio of thyroid autoantibodies observed in individuals affected by the condition. No clinical manifestations of AITD have been described in this group, although a hypothesis has been advanced.
We present the case of a 52 year-old Caucasian gentleman who was diagnosed with RTH following a presentation with a ventricular tachycardia. Karyotyping revealed a G332E mutation of the beta sub-unit. He had been undergoing long-term follow up in the endocrinology clinic. Cardiac arrhythmia control was achieved with Triac (1.4mg total daily dose), presumably mediated by a reduction in thyroid hormone drive to his α-α receptors. His liver (β-β receptor) associated dyslipidaemia was addressed with Rosuvastatin (20mg) and Ezetimibe (10mg). This had given him fifteen years of stability.
In May 2015, he started to complain of “pain and grittiness” affecting his eyes. Examination revealed bilateral chemosis and signs consistent with a thyroid-associated orbitopathy. TSH receptor antibodies were elevated (10.3units/mL (0-0.3unit/ml), previously negative). He was referred to the ophthalmology department for further assessment and following an orbital MRI, which confirmed symmetrical enlargement of the extraocular muscles, a diagnosis of a thyroid-associated opthalmopathy was made.
In view of his previous cardiac history, he underwent a full cardiological assessment prior to commencing treatment with pulsed methylprednisolone (500mg once weekly for six weeks). This has resulted in an improvement in his eye symptoms and his TSH receptor antibody levels have started to normalise (1.0units/mL). The long-term prognosis is however difficult to predict.