Central hyperthyroidism combined with Graves' disease: case series and review of the literature

Background: Central hyperthyroidism is characterized by elevated free thyroid hormone and unsuppressed thyroid-stimulating hormone (TSH), and this laboratory feature includes TSH-secreting pituitary adenoma (TSHoma) and resistance to thyroid hormone β (RTHβ). Central hyperthyroidism combined with Graves' disease (GD) has been rarely reported.

Case report: We describe three patients with TSHoma combined with GD and one patient with GD combined with RTHβ and pituitary adenoma. These three patients with TSHoma combined with GD showed elevated thyroid hormone, while TSH level was normal or elevated, and TSH receptor antibodies were positive. After thyrotoxicosis was controlled, they all underwent transsphenoidal surgery. We also describe a patient with an initial presentation of GD who developed hypothyroidism after anti-hyperthyroidism treatment and TSH was inappropriately significantly increased. His head magnetic resonance imaging revealed a pituitary adenoma. Genetic testing confirmed a heterozygous mutation in the thyroid hormone receptor β gene c.1148G>A (p.R383H). After levothyroxine and desiccated thyroid tablet treatment, the TSH level decreased to normal.

Conclusion: These four cases highlight the need to consider the diagnosis of GD combined with central hyperthyroidism when faced with inconsistent thyroid function test results, illuminating the specific diagnostic and therapeutic challenges of coexisting primary and central hyperthyroidism. Finally, we propose clinical management for central hyperthyroidism combined with GD.