Serum T3 and T4 were measured in 34 patients scheduled elective surgery with general anesthesia, who were divided into two groups (enflurane group: 12 propofl: 22). No clinical signs of thyroid disturbances could be observed preoperatively in the
patients. Anesthesia was induced with thiopental 5 mg/kg in enflurane group; propofol 2 mg/kg in propofol group, and maintained with O2 2 L/min, N2O 2 L/min, enflurane (1.0-2.5%) in enflurane group; O2 2 L/min, N2O 4 L/min and continuous
controlled
infusion of propofol (50-150 mcg/kg/min) in propofol group. Blood samples were collected 5 minutes after arrival in operating room, 1 minute after induction, 5 minutes after intrbation, 1 minute after skin incision, during operation and 10
minutes
after
extubation. Blood samples were centrifused and serum was taken from each sample. Determinations of T3 and T4 were performed using enhanced chemiluminescence immunoassay (ELIA). Comparisons of our results were made using repeated measures analysis
of
variance, paired students t-test and statistically significant when p value was less than 0.05.
@ES The results are summarized as follows:
@EN 1) In enflurane group, serum T3 levels showed a decreasing tendency after extubation compared to baseline. Decreasing serum T4 after administration of thiopental could be considered statistically significant and serum T4 levels showed a
decreasing
tendency after extubation compared to baseline.
2) In propofol group, serum T3 levels showed a decreasing tendency after extubation compared to baseline. Rises in serum T4 after incision and extubation could be considered statistically significant.
Based on these results, no direct negative influence of propofol need be expected on T4/T3-metabolism in euthyroid patients. However, the changes in these hormones, although with in the physiological range here, indicate that propofol may
adversely
influence their levels in the presence of manifested thyroid disease.
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