Assays for insulin-like growth factors and their binding proteins: practicalities and pitfalls.

Insulin-like growth factors (IGFs) are growth hormone-dependent anabolic peptides that circulate in biologic fluids complexed to a family of IGF binding proteins. Measurement of the serum concentrations of IGF peptides and IGF binding proteins has proved to be an effective means of evaluating functional growth hormone status and makes it possible to establish a diagnosis of IGF deficiency.