The Physiology of Insulin-like Growth Factor Binding Protein-3 and Its Role in Disorders of the Growth Hormone Axis

抄録

Insulin-like growth factor-I (IGF-I) is the main mediator through which GH effects growth. The mechanisms underlying the growth-promoting effect of GH and/or IGFs are not yet fully understood. During the post-natal period, IGFs circulating in the body are mainly found in the IGFBP-3 complex. Both IGF-I and IGFBP-3 are qualitatively -though not quantitatively-regulated by the same factors. Thus, it might not only be their absolute levels which determine the metabolic effects of IGFs but also their quantitative relations to IGFBPs. Levels of IGFBP-3 vary according to age and sexual development, nutritional status, GH secretion, and liver and kidney function. As the kinetics of IGFBP-3 are relatively slow, unlike IGF-I, it leads to the stability of blood levels. Insight can thus be gained into the GH secretory status of short children. Besides this, a clear differentiation can be made between normal or pathological IGFBP-3 levels. This means that not only GH insufficiency but GH overproduction as well can be diagnosed easily, a fact which speaks for itself with regard to screening tests and follow-up check-ups during GH treatment. IGFBP-3 measurements are a practical tool in dealing with cases of impaired IGF synthesis, in which GH secretion is either normal or high.