The IGF system: new developments relevant to pediatric practice.

In the 50 years since the initial report of the 'sulfation factor' or 'somatomedin'hypothesis, the IGF system has established itself as the primary mediator of both intrauterine and postnatal growth in mammals. IGF deficiency (IGFD) has emerged as an important clinical diagnosis: secondary IGFD results from insufficient production of GH and is characterized by postnatal growth failure; primary IGFD can result from abnormalities of the GH receptor or GH signaling cascade, or from mutations or deletions of the IGF-I gene. Monitoring IGF production during short-term IGF generation tests or during chronic GH therapy can provide a means for evaluating the efficacy and safety of GH treatment. IGF-I, either alone or in combination with IGF binding proteins, is the treatment of choice for primary IGFD and may have a role in treatment of idiopathic short stature when accompanied by decreased serum concentrations of IGF-I.