Endocrine Abstracts

Introduction: Ophthalmopathy, the most common extrathyroidal manifestation of Graves’ disease, occurs in 5% of cases in the absence of hyperthyroidism. Amiodarone, an iodine-rich antiarrhythmic drug, influences thyroid function, causing thyrotoxicosis or hypothyroidism, but its effect on thyroid autoimmunity is still a matter of debate.

Case report: We report the case of a 58-year-old woman, suffering from non-sustained ventricular tachycardia, treated inconstantly with amiodarone for 27 years. Thyroid function was normal until January 2014 when she developed amiodarone induced hypothyroidism (TSH=24 mUI/l) with negative thyroid autoantibodies anti-Tg=0.1 UI/ml (<4), anti-TPO=1.0 UI/ml (<20), and substitutive therapy with L-thyroxine 50 μg/day was started. Three months later the patient stopped L-thyroxine at a TSH=0.16 mUI/l. Subsequent evaluation in August showed normal thyroid function (TSH=3.4 mUI/l). In October she was referred to our Department for periorbital oedema, increased tearing, diplopia, mild conjunctival injection. The laboratory tests showed euthyroidism (TSH=3.88 mUI/l), negative anti-Tg and anti-TPO antibodies, positive TRAb=6.8 UI/l (<1). Thyroid ultrasound was normal. The eye examination revealed a clinical activity score of 4, decreased left eye motility, vertical diplopia and Hertel exophtalmometer measurements were 15 mm on the right and 17.5 mm on the left eye. The orbital CT-scan showed thickening of the left eye inferior and medial rectus muscle. The patient was treated with six pulses of intravenous methylprednisolone, 250 mg once a week, but after the third pulse she developed symptomatic bradycardia. The cardiologist recommended to stop amiodarone. The remaining pulses were well tolerated, with improvement of the eye symptoms.

Conclusion: In our case this variable thyroid status and the occurrence of euthyroid Graves’ ophthalmopathy (GO) sustain the finding that in susceptible individuals amiodarone may precipitate thyroid autoimmunity due to its cytotoxic effect with a greater release of thyroid antigens. Patients with euthyroid GO need regular follow-up, because the eye involvement may develop before the appearance of clinical or laboratory signs of hyperthyroidism.