IGF1 and hyperthyroidism: On the other hand, the coexistence of GHPA can also aggravate the hyperthyroidism caused by GD and may even induce or aggravate GO, while the hyperthyroidism of GD improves with the decrease of GH/IGF-1 after TSS or SSA treatment, suggesting that the GH–IGF-1 axis promotes growth, thyroid function, and thyroid hormone metabolism.