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. Here, IGF1 is linked to hyperthyroidism.