Endocrine Abstracts

Introduction

Graves’ disease is found in 5% of patients with myasthenia gravis. It’s a described but rare association that addresses pathophysiological, diagnostic and management challenges. We report a case of Graves’ disease revealed by an orbitopathy in a patient with coexisting mysthania gravis.

Case report

A 40-year-old woman with established myasthenia gravis presented to the emergency room with upper eye lid ptosis and bilateral eye protrusion for 3 months. It was associated with a two-week history of palpitations, tremors, irritability and moderate weight loss. Thyroid function was assessed, showing suppressed TSH (0.01 µUI/ml), elevated free thyroxine (46 pmol/l) and positive autoantibody tests. Ultrasound found an enlarged hypervascular thyroid gland. The diagnosis of graves’ ophtalmopathy with coexistent myasthenia gravis was retained. Treatment initially consisted of antithyroid drug by carbimazol before performing a thyroidectomy.

Discussion

The association between Graves’ disease and myasthenia gravis has been described for decades, but the exact mechanism for such coexistence is not clearly understood. It seems, however, that autoimmunity and genetic factors play a role in this association. The symptoms of the two conditions may overlap. Graves’ ophthalmopathy shares with myasthenia gravis the presence of extraocular muscle damage but is differentiated by the presence of a red, inflammatory eye and exophthalmos. Treatment of the two conditions can be challenging, as the treatment of an entity can worsen the other. Propanol is contraindicated in this case and radical treatment of hyperthyroidism is recommended.

Conclusion

The association between Graves’ disease and myasthenia gravis has been recognized. The distinction between the two autoimmune diseases can be difficult as symptoms may overlap. This association should be known by physicians as it implies diagnostic and therapeutic measures.