Growth hormone (GH), or somatotropin, is a peptide hormone that serves as the primary architect of human growth. It functions by stimulating the liver to produce Insulin-like Growth Factor 1 (IGF-1), which acts on the growth plates of long bones in children.

In 2026, medical understanding emphasizes that GH is a "metabolic regulator" throughout the entire lifespan. It promotes protein synthesis, facilitates the breakdown of fats (lipolysis), and helps maintain a healthy balance between muscle mass and adipose tissue. For individuals with GHD, the absence of this hormone leads to more than just short stature; it results in reduced physical stamina, altered cholesterol levels, and a decrease in bone mineral density.