Endocrine Abstracts

Introduction: Graves’ orbitopathy is usually associated with Graves’ Disease, which is typically characterized by hyperthyroidism and goiter. However, in rare situations, Graves’ disease can also present with hypothyroidism and orbitopathy.

Case report: Male, 38 years old, followed by his ophthalmologist for thyroid orbitopathy (exophthalmos right>left and conjunctival hyperaemia since 1 year ago) associated with asthenia, tiredness and weight gain. He was referred to endocrinology consultation because he presented TSH elevated (62.75 μUI/ml, reference values (RV): 0.35–4.94) with normal FT₄ 0.70 ng/dl (RV: 0.70–1.48) and normal FT₃ 2.95 pg/ml (RV 1.71–3.71) and high levels of anti-thyroid and TSH-receptor autoantibodies (TRAbs) (5.2 U/l (RV: 0–1.8)). Thyroid ultrasonography showed a gland with normal dimensions, heterogeneous and pseudonodular texture, suggesting thyroiditis. The patient denied any previous treatment. He started therapy with levothyroxine and the dose was increased as needed. It was accompanied by improvement of hypothyroid symptoms. Six months later, he had normal TSH and TRAb’s=3.9 U/l (RV: 0–1.8). A year after starting therapy, symptoms reappeared and analytically he presented again with hypothyroidism (TSH=14.71; FT₃ and FT₄N) and TRAB’s levels >40.0 U/l.

Discussion: It has been described in literature different types of TRAbs, which are capable of inducing two distinct clinical syndromes: thyroid-stimulating autoantibodies and TSH-blocking autoantibodies. In this patient with Graves’s orbitopathy, a predominance of blocking type TRAbs vs stimulatory type may be a possible explanation for the presence of hypothyroidism. Although, we can’t exclude the possible contribution, at least at some degree, from the gland’s destruction (suggested by high titres of anti-peroxidase/anti-thyroglobulin autoantibodies and the findings suggestive of thyroiditis in ultrasound). Thus, the determination of TRAbs subtype is of particular interest in these less common forms of presentation of thyroid autoimmune pathology.