Any stress, including that from a precise procedure, causes a dramatic release of adrenocorticotropic hormone (ACTH) from the anterior pituitary that, consequently, directs the release of cortisol from the adrenal cortex. The circulating cortisol level remains elevated to two to five times the normal level for approximately 24 hours following the procedure52 and acts upon skeletal tissue to create about break down of skeletal muscle tissue proteins into proteins for localized wound healing and for glucose production by the liver.
Concomitantly, epinephrine and norepinephrine are released and remain elevated for approximately 48 hours, stimulating breakdown of liver glycogen with release of glucose for cellular energy needs through the immediate postoperative period.53 The upsurge in epinephrine suppresses release of insulin,54 glucagon concentrations rise,55 and the liver is stimulated to begin gluconeogenesis to go back to preoperative levels and to guide the power requirements of the healing process. Additional reactions to surgery include alterations in water regulation mediated by release of antidiuretic hormone and aldosterone, which increases water reabsorption in the renal collecting ducts and increases sodium retention in the renal tubules, respectively.56,57 It’s thought that the release of these hormones is stimulated by signals from blood pressure– and osmolarity-sensitive receptors.53 This diminished capability to excrete water in the first postoperative period results in temporary weight gain and a return to normal blood volume.58 After the aforementioned events, the individual enters a metabolic transition period of 1 or 2 days where your body begins to show from corticosteroid- and epinephrine-initiated breakdown to rebuilding and healing. During this time, shedding of the retained water is effected, while conserving nitrogen and potassium. The slow means of healing and regaining weight is now able to begin and is marked by protein synthesis, wound healing, buildup of muscle tissue, and increasing strength.53 Many of these processes occur with a fair amount of predictability in the adequately nourished adult patient. The method is imperiled, as is the prognosis for full recovery, if the adult is elderly or malnourished.