Changes within the GH/IGF-I/IGFBP axis in critical illness.

Interest in the somatotropic axis, with its complex network of interactions, during critical illness started only a few decades ago. The distinguished neuroendocrine features of prolonged critically ill patients were not differentiated from those during the acute phase until the 1990s. This incomplete understanding of the somatotropic axis has contributed to some disastrous results. Aiming to stimulate the somatotropic axis without a proper preceding neuroendocrine diagnosis should be held obsolete, because recent data indicate that the patient with the best anabolic parameters may not necessarily be the most favored to survive the ICU stay. Moreover, the fascinating link between regulators of carbohydrate metabolism, such as insulin and insulin-like growth factor 1, and the somatotropic axis may lead to future therapeutic possibilities.