We have performed paired isotopic studies in four patients undergoing resection of early
colorectal cancer and four having removal of
parathyroid adenomas. Kinetic measurements of
protein and
glucose metabolism were made before resection and at home 10 weeks after surgery. During
convalescence there were major changes in both groups in
glucose metabolism and the hormonal milieu despite no alterations in
protein kinetics or metabolic rate. In particular, the rate of
glucose production doubled from (mean +/- s.e.m.) 14.8 +/- 1.3 to 28.1 +/- 2.5 mumol kg-1 min-1 (P less than 0.01), the percentage of available
glucose undergoing oxidation decreased from 35.5 +/- 3.9 to 21.5 +/- 2.9 per cent (P less than 0.05) and the percentage of
glucose undergoing recycling to
lactate increased from 20.1 +/- 10.0 to 52.9 +/- 2.3 per cent (P less than 0.05). During
convalescence the basal plasma
insulin concentration was significantly higher (P less than 0.05) and there was a proportionately smaller response to
glucose infusion. The convalescent state was also associated with an elevation in serum
cortisol from 291 +/- 54 to 496 +/- 75 nmol litre-1 (P less than 0.05). The values for resting energy expenditure were not significantly different from the predicted energy expenditure in either the preoperative or the convalescent groups. We conclude that (a) there is a marked increase in both
glucose production and
glucose recycling to
lactate in
convalescence from clean uncomplicated surgery, and this is associated with a decrease in the percentage of
glucose uptake oxidised; (b) a relative hyperinsulinaemia is seen in convalescent patients and is associated with decreased responsiveness to a
glucose load; (c) the plasma
cortisol level is significantly elevated after 10 weeks of
convalescence; and (d) convalescent patients do not have elevated rates of
protein catabolism or energy expenditure.