Influence of age on the endocrine-metabolic response to surgery.

The pathogenesis of the increased operative risk in elderly patients is unknown. From a theoretical point of view, a change in endocrine-metabolic response might be involved. In the present study, a battery of hormonal and metabolic variables were measured in eight young and eight elderly healthy males undergoing elective inguinal hernial repair under general anesthesia. Blood was drawn before induction of anesthesia, at skin incision, and one, two, and six hours after skin incision. The findings were: 1) Plasma cortisol increase was significantly higher in elderly than in young controls. 2) Plasma renin level was lower in old age, but renin-aldosterone and electrolyte response patterns were alike in the two groups. 3) Thyroid parameters, in terms of serum T4, serum T3, serum rT3, and T3-resin uptake, responded normally to surgery and showed no age-related differences. 4) The hyperglycemic response was not significantly influenced by age indicating unchanged glycoregulatory mechanisms also verified by determinations of plasma catecholamines, cAMP, and insulin. 5) Blood lymphocyte count was constantly lower in elderly than in young and decreased with time, but the age-related difference was not significant. 6) Blood polymorphonuclear leukocytes showed an increase of the same magnitude in both age groups, although at a significantly slower rate in the elderly. It is concluded that age affects some aspects of the initial endocrine-metabolic response to surgery.