Overview of the endocrine response to critical illness: how to measure it and when to treat.

The assessment and manipulation of the endocrine system in patients with critical illness is one of the most complex and controversial areas in endocrinology. Severe acute illness causes dramatic changes in most endocrine systems. This can lead to considerable difficulty in recognising pre-existing endocrine disorders in severely ill patients. Critical care itself might also induce types of endocrine dysfunction not seen outside the critical care unit. It is important to clarify whether or not such endocrine dysfunction occurs. Where it does occur it is also important to determine whether endocrine intervention is useful in improving outcome. There is also the issue of whether endocrine manipulation in critically ill patients without endocrine dysfunction could benefit from endocrine intervention, e.g. to improve haemodynamics or reverse a catabolic state. This review will discuss some of these contentious issues. It will highlight how endocrine assessment of a patient with critical illness differs from that in other types of patient. It will emphasise the added need to place the biochemical assessment and its interpretation in the context of the patients underlying condition.