Glucagon, insulin, cortisol, and growth hormone levels following major surgery: their relationship to glucose and free fatty acid elevations.

Circulating hormone and substrate levels were measured in 7 patients at regular intervals before, during and after pulmonary surgery. During surgery, cortisol and growth hormone were significantly elevated, pancreatic glucagon was unchanged and insulin was depressed. One and two days after surgery, growth hormone had almost returned to preoperative fasting values, but cortisol, insulin and glucagon levels were significantly increased. The mean insulin:glucagon molar ratio declined from a preoperative fasting value of 3.2 +/- 0.5 (+/- SEM) to 1.7 +/- 0.4 during operation but was within normal limits 1 and 2 days after surgery due to a parallel rise and fall in plasma insulin and glucagon. Plasma glucose was elevated both during operation and for several days thereafter, whereas free fatty acid levels were increased only during operation. Thus, there was no consistent relation between insulin:glucagon ratio or any of the hormone levels and the observed elevations in plasma glucose and free fatty acids. It is concluded that neither any of the hormones assayed nor the insulin:glucagon ratio was the primary determinant of plasma glucose and free fatty acid responses to surgery. Rather, fuel homeostasis appeared to result from the combined effects of glucagon, insulin, growth hormone, cortisol and adrenergic activity.