Abstract
PURPOSE: The coexistence of growth hormone-secreting pituitary adenoma (GHPA) and Graves' disease (GD) is rare. This study aimed to investigate the relationship between growth hormone (GH)/insulin-like growth factor 1 (IGF-1) levels and thyroid function in patients with GHPA combined with GD and to explore the underlying mechanisms. METHODS: Eleven patients with GHPA combined with GD during 2015-2022 were collected by searching the medical record system of Beijing Tiantan Hospital, Capital Medical University. Changes in GH/IGF-1 levels and thyroid function were compared before and after the application of antithyroid drugs (ATD) and before and after transsphenoidal surgery (TSS) or somatostatin analog (SSA) treatment, respectively. RESULTS: After the application of ATD, with the decrease of thyroid hormone levels, GH/IGF-1 levels also decreased gradually. In patients without ATD application, after surgery or SSA treatment, thyroid hormone levels decreased as GH/IGF-1 decreased. CONCLUSION: Hyperthyroidism due to GD promotes the secretion of GH/IGF-1, and when thyroid hormone levels were decreased by the use of ATD, GH and IGF-1 levels were also decreased, suggesting that thyroid hormones may influence the synthesis and secretion of GH/IGF-1. The use of ATD to control thyrotoxicosis before TSS is not only beneficial in reducing the risk of anesthesia but may help to promote biochemical control of GHPA. On the other hand, high levels of GH/IGF-1 in patients with GHPA also exacerbate GD hyperthyroidism, which is ameliorated by a decrease in GH/IGF-1 levels by TSS or SSA treatment, suggesting that the GH-IGF-1 axis promotes growth, thyroid function, and thyroid hormone metabolism.