Insulin-like growth factor binding protein 3 (IGFBP-3) is the main carrier of somatomedin C (also called insulin-like growth factor-1, or IGF-1) in the body. Blood levels of both these proteins are controlled by human growth hormone (hGH), a hormone that’s produced by the pituitary gland, a pea-sized gland in the brain that works with the endocrine system. The pituitary gland regulates growth and the function of other glands.
But IGFBP-3 is more than just a transporter. It also helps extend the life of somatomedin C in the blood and helps control its effects on body tissues.
Levels of IGFBP-3 are highest during childhood and puberty, then they decrease during adulthood. Levels also may be affected by sexual maturation and nutritional status.