Insulin-like growth factors, nutrition and growth.

Nutritional status is a key factor in the regulation of human linear growth. The growth hormone (GH)-IGF axis consists of a cascade of finely tuned molecular mechanisms which are vulnerable to protein-calorie deficiency. The most notable evidence for this is the presence of IGF-1 deficiency, that can be caused by failure of a number of processes including abnormal pituitary GH secretion, decreased GH binding to its receptor (GHR), post-GHR signal transduction, IGF-1 gene transcription, IGF binding protein (IGFBP) deficiency and decreased IGF-1 binding to its own receptor (IGF1R). Nutritional deficiency is seldom present as an isolated pathogenesis. In diarrhoeal states, intercurrent infection is frequently present which impairs the function of the growth plate. In chronic inflammatory disorders, where nutritional deficiency may be present due to increased energy expenditure, co-existing excess cytokine production also disrupts the GH-IGF-1 axis causing a complex mixed pathogenesis.