What is IGF-1?

IGF-1 is one of the main hormones involved in the growth of muscles and bone.  It also prevents other cells from “cell suicide” and has some insulin-like effects.

IGF-1, also known as Somatomedin C, is a polypeptide hormone similar in structure to insulin and primarily produced in the liver.  It is one of the main mediators of the actions of growth hormone in promoting muscular and skeletal growth. IGF-1 is itself a powerful anabolic hormone, and it also prevents premature cell death by inhibiting apoptosis. Because of its similarity to insulin, it also weakly activates the insulin receptor and therefore has insulin-like effects when present in large quantities. Circulating IGF-1 is almost 100% bound to IGF binding proteins (IGFBP), the most abundant of these being IGFBP-3. These binding proteins stabilize IGF-1, prolonging its half-life in the bloodstream. Blood levels of IGF-1 are low in young children, peaking during the pubertal growth spurt and then declining steadily with age. IGF-1 is stable in whole blood dried on filter paper and therefore can be conveniently and accurately measured in dried blood spots.