Content area
Full Text
Intensive Care Med (2015) 41:14771479DOI 10.1007/s00134-015-3771-8 WHATS NEW IN INTENSIVE CARE
http://crossmark.crossref.org/dialog/?doi=10.1007/s00134-015-3771-8&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s00134-015-3771-8&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s00134-015-3771-8&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s00134-015-3771-8&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s00134-015-3771-8&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s00134-015-3771-8&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s00134-015-3771-8&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s00134-015-3771-8&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s00134-015-3771-8&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s00134-015-3771-8&domain=pdf
Web End = Johannes Hoand Jan Bakker Richard A. Feelders
Whats new on the HPA axis?
Received: 24 February 2015Accepted: 22 March 2015Published online: 8 April 2015 The Author(s) 2015. This article is published with open access at
Springerlink.com
J. Hoand ()) R. A. Feelders
Section of Endocrinology, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands e-mail: [email protected]
J. BakkerDepartment of Intensive CareAdults, Erasmus Medical Center, Rotterdam, The Netherlands
Introduction
The human body depends on an integrated neuro-endocrine response in order to adapt to external and internal stressors. In critical illness this stress response coordinates endocrine, neural, cardiovascular and immune systems with the aim to maximize survival chances. The hypothalamuspituitaryadrenal (HPA) axis, which also includes elements producing the neurohypophysial hormone argininevasopressin (AVP), is one the key effectors within this system [1]. Relative HPA or AVP deciency contributes to cardiovascular collapse in critically ill patients, leading to the rationale of therapy with these hormones in shock. Recent developments have implicated copeptin, a by-product of the AVP precursor, as a novel biomarker for early stages of critical illness that could inuence clinical decision-making.
Physiology of the HPA axis
A wide variety of circulating local and neurosensory signals control hypothalamic corticotrophic-releasing
hormone (CRH) and AVP release from the paraventricular nucleus (PVN). Parvocellular neurons co-secrete CRH and AVP into the hypophysial portal circulation. These peptides reach the adenohypophysis and synergistically stimulate the release of adrenocorticotrophic hormone (ACTH). ACTH increases adrenocortical production and the release of cortisol, the main glucocorticoid in humans with widespread homeostatic effects in many organs. In a recent elegant study, Boonen et al. demonstrated that elevated cortisol levels in critical illness result from a reduced cortisol metabolism [2] despite suppressed ACTH and cortisol pulse secretion [3].
AVP is also produced in the magnocellular neurons of the PVN and directly secreted into the bloodstream through their axons in the posterior pituitary (Fig. 1a). The principal effects of circulating AVP are vasoconstriction through its V1a receptor in vascular...