Growth hormone (GH) is a protein-based poly-peptide hormone. It stimulates growth and cell reproduction and regeneration in humans and other animals.

It is a 191-amino acid, single-chain polypeptide hormone that is synthesized, stored, and secreted by the somatotroph cells within the lateral wings of the anterior pituitary gland.

Somatotropin refers to the growth hormone produced natively and naturally in animals, whereas the term somatropin refers to growth hormone produced by recombinant DNA technology, and is abbreviated "rhGH" in humans.

The formation of anti-hGH antibodies influenced the pharmacokinetics of hGH, but it could be prevented by immunosuppressive therapy.