Unilateral Thyroid Involvement in Graves' Disease: A rare presentation of Graves’ Disease

Graves' disease is a rare autoimmune disorder characterized by increased hormone production leading to clinical signs of hyperthyroidism, most cases present with different degrees of TSH suppression, accompanied by elevated FT4. Thyroid scintigraphy commonly reveals an enlarged goiter with diffuse increased iodine uptake. This study presents the case of a 50-year-old woman with a clinical history of Graves' disease presenting with suppressed TSH and elevated FT4 combined with clinical signs of hyperthyroidism (tachycardia and peripheral tremors). Thyroid imaging showed increased unilateral uptake on scintigraphy with no visible nodules on ultrasound. The patient showed an adequate initial response to methimazole, with disease relapses after dose reduction. The patient was able to maintain euthyroidism with continued antithyroid drug use. Single lobe involvement of Graves' Disease is a rare phenomenon attributed to the autoimmune process combined with acquired variations impacting a specific lobe. Clinically, patients are present with different degrees of hyperthyroidism. In most cases, the use of antithyroid drugs provides adequate disease control, with patients subjected to definitive treatment presenting a higher risk of disease recurrence in the contralateral lobe. This report shows a case with a favorable response to continue antithyroid drugs treatment after disease relapse. The findings highlight the rare occurrence of unilateral thyroid gland involvement in Graves' disease. Also, suggest a favorable response to continue antithyroid treatment for patients exhibiting relapses.