The comparison of the effects of isoflurane and propofol anaesthesia on serum TSH, T3 and T4 levels

The effects of surgery and anaesthesia on endocrine functions are well known. Hovvever detailed studies about the effects of propofol on thyroid functions are absent. The aim of this study is to study the effect of propofol anaesthesia on thyroid hormones and to compare it with isoflurane anaesthesia. This study was performed on ASA l-ll class.euthyroid 30 patients vvithout endocrine pathologies. After premedication, induction was performed in the first group (n=15) with i.v. 0,05 mg fentanyl, 5-7 mg thiopental; in the second group (n=15) with i.v. 0,05 fentanyl, 2 mg/kgpropofol. Patients were intubated with i.v. 1 mg/kg succinylcholine, maintenance was done with %1-1,5 isoflurane %50 O2-%50 N2O + atracurium in the first group and 6-10 mg/kg/h propofol + %50 O2+%50 N2O atracurium in the second group. Blood samples were obtained before induction(control), after induction, first hour intraoperatively on postoperative 2nd and 24 th hours chemiluminesance method was used for the plasma TSH,TT3, FT3,İ7'4, FT4 analyses. The TSH serum levels did not change in both groups. A significant decrease in TT3, FT3 serum levels in the 24th hour postoperatively was observed in the first group (p<0,01), (p<0,05).This decrease, in the first group was significant betvveen the groups (p<0,05). Significant increases in serum TT4 levels occured first hour intraoperatively in the first group (p<0,05). No difference was found betvveen the groups. Asignificant increases in serum FT4 levels was recorded in the 1st hour intraoperatively and 2nd hour postoperatively in the first group(p<0.01) (p<0.05)The increases was significant betvveen the groups (p<0.01)(p<0.05). We conclude that propofol is saf e alternative agent to isoflurane in hyperthyroid patients.