IGF-1 (Insulin-like growth factor1), that was once called somatomedin-C, is a polypeptide hormonal protein that has same molecular structure as insulin. IGF-1 plays a very important role in child’s growth and maintains to have anabolic changes in adults. It consists of seventy amino acids in a distinct chain with 3 intermolecular disulfide bridges. It has a molecular mass of 7649 Daltons and is produced mainly by the liver as the endocrine hormone and in target tissues in an autocrine/paracrine fashion. Its production is increased by the growth hormones and retarded by the deficiency of growth hormone receptors, under nutrition, malfunctioning of the downstream signaling or insensitivity of growth hormones etc.