Per- and postoperative changes in the concentration of serum thyreotropin under general anaesthesia, compared to general anaesthesia with epidural analgesia.

In 18 patients scheduled for lower intraabdominal surgery (hysterectomy), changes in thyreotropin (TSH) thyroxine (T4), triiodothyronine (T3) binding of thyroid hormones to plasma proteins (T3-uptake) and glucose in serum were evaluated. In eight patients afferent neurogenic impulses from the surgical area were blocked (Th4-S5) with bupivacaine 0.5% infused continuously into the epidural space from the start of the operation until 6 h postoperatively. All patients received general anaesthesia with thiopentone, pethidine, pancuronium and nitrous-oxide plus oxygen. The patients receiving epidural analgesia had no increase in plasma-TSH, compared to the other group, which had a significant (P less than 0.05) increase peroperatively. The patients receiving epidural analgesia were pain-free and the normal stress-induced increase in plasma-glucose was abolished. Concerning T3 we found a significant decrease in both groups and a steady level of T4- and T3-uptake without significant fluctuations. Thus it can be concluded that the effects of surgical trauma on plasma-TSH concentration are markedly similar to the effects of other anterior pituitary hormones, i.e. HGH, prolactin and ACTH.