Endocrine Abstracts

We report the case of a Caucasian woman presenting with a challenging differential diagnosis of ophtalmopathy. The patient was diagnosed with Graves’ disease during postpartum at the age of 28 (TSH<0.001 U/ml; FT3 6.7 ng/dl; FT4 2.2 ng/dl; TSAb 15 U/l). Besides 16 pack-year smoking history, no other previous disease was known. At examination, exophthalmos grade I/III with bilateral lid retraction was evident. Persistency of the disease despite optimal use of medical antithyroid therapy led to radioactive iodine ablation (10 mCi) at the age of 34.Three months afterwards, hypothyroidism was detected on blood tests results (TSH: 12 U/mL; Free T4: 0.7 ng/dl) and therapy with 100 μg of L-thyroxine was initiated. Two months after therapy, thyroid function was normalized (TSH: 1.3 U/ml; Free T4: 1.1 ng/dl). Exophthalmia persisted, even though TSAb title was virtually undetected (0.6 U/l). At the age of 45, there was onset of binocular vertical diplopia and blurred vision. Upon administration of 500 mg ev Methylprednisolone, symptoms were only transiently relieved and thereafter rapidly worsened. Persistent diplopia and mild exophthalmos were confirmed in ophthalmology appointments. The patient was clinically euthyroid, thyroid function tests were normal under Levothyroxine replacement and TSAbs remained negative. Computed tomographic scan and magnetic resonance imaging of the orbits showed symmetric bilateral exophthalmia (grade I/III) with inferior rectus muscle thickening on the right eye, consistent with Graves’ disease. However, the single fiber electromyography revealed a moderate defect in neuromuscular transmission. Anti-acetylcholine receptor antibodies were 14 times the reference value, compatible with the diagnosis of Myasthenia Gravis. Moreover, the patient denied fatigue, movement disorders or other neurological symptoms. By reporting this case, we would like to draw attention for a possible, although rare, association of myasthenia gravis and Graves’ ophthalmopathy and stress the importance of a clinical judgment.