Activation of pituitary axis according to underlying critical illness and its effect on outcome

Purpose: Critical illness is a life threatening condition inducing a severe acute physical stress. The aim of the study was to investigate the activation of pituitary axis early after ICU admission in patients with critical illnesses of different etiology and its association with outcome. Materials and methods: Patients admitted for acute respiratory distress syndrome (ARDS), severe traumatic brain injury (TBI), subarachnoid hemorrhage (SAH) and neurocritically ill patients at the moment of brain death (BD) diagnosis were included in the present post-hoc analysis. On day 1, 2–3 and 4–5 after admission the following pituitary axes were assessed: hypothalamic-pituitary-adrenal, hypothalamic-pituitary-thyroid, somatotroph, prolactin and copeptin. ICU mortality was used as outcome measure. Results: One hundred-thirteen critical ill patients were studied. Thyroid axis suppression and activation of copeptin axis were the most frequent pituitary hormone alterations, present in almost 60% of patients. Activation of the hypothalamic pituitary adrenal axis was a predictor of ICU mortality independently from the underlying critical illness [OR 3.952 (C.I.95% 1.129–13.838)]. Conclusions: Pituitary axis function is frequently altered early after ICU admission, the magnitude of hormonal response being different according to the underlying critical illness. The activation of the hypothalamic pituitary adrenal axis was a strong predictor of ICU mortality.