ENDOCRINE ASPECTS OF THE METABOLIC RESPONSE TO SURGICAL OPERATION.

SURGICAL OPERATION OR any other form of physical injury in a previously healthy person initiates a series of metabolic and endocrine processes which are associated with recovery and normal convalescence. Two hundred years ago John Hunter appreciated that the recovery from injury followed a distinctive pattern when he wrote: " There is a circumstance attending accidental injury which does not belong to disease, namely, that the injury done has, in all cases, a tendency to produce both the disposition and means of cure " (Hunter, 1861). It is now almost 100 years since Bauer (1872) demonstrated that the concentration of nitrogen in the urine was increased after a simple haemorrhage. It was shown later (Hawk and Geis, 1904) that a similar increase occurred after injury in which the loss of blood was negligible. Cannon (1929) was the first to recognize the importance of the endocrine system in the response to injury. He introduced the concept of a neuroendocrine response to stress and described an increase in the activity of the sympathetic nervous system and in the output of adrenaline-like substances. Cuthbertson (1932) observed that body protein was broken down more rapidly than it was formed after injury and nitrogen appeared in excess in the urine. The increased excretion of nitrogen lasted several weeks after severe injuries such as fractures of long bones and only a few days after minor trauma. Selye (1946) attempted to find a single explanation for the endocrine and metabolic response to stress. He postulated that increased adrenocortical activity initiated and controlled the total body response to stress. Much of the current knowledge of the endocrine and metabolic changes in the postoperative period has come from the detailed balance studies reported by F. D. Moore (1959). The ability accurately to measure the output of many adrenal steroids has added much to the interpretation of the physiology of injury.