Clinical relevance of serum measurements of insulin-like growth factors and somatomedin binding proteins.

With the presently available RIAs, serum levels of IGF-I, IGF-II and somatomedin binding protein can be determined specifically. Basal IGF-I and binding protein levels are low in GH deficiency, and normality of these parameters virtually excludes the condition. If, in a given clinical situation, auxological criteria and IGF-I (binding protein) levels suggest GH deficiency but the diagnosis is rejected by conventional stimulation tests, a further diagnostic work-up is needed, including measurements of spontaneously secreted GH. IGF measurements may serve as tools to disclose the unknown pathogenesis in growth disorders. Short-term responses of IGFs to exogenous GH may assist in defining the GH doses required to induce long-term growth.