The liver has various endocrine functions such as hormone and hepatokine production. It is also involved in the metabolism of endocrine hormones such as thyroid hormones, steroid hormones, and glucagon-like peptide-1. It assists in both activation and inactivation of these hormones. The liver also generates IGF-1 in response to growth hormone stimulation. Amino acids are also regulated by the liver via negative feedback on pancreatic a-cells.