RETURNEffects of Neuroleptanesthesia and Upper Abdominal Surgery on Pituitary-Thyroid Functions
Shinya Hori, Keiichiro Ueda and Chiaki Shigemasa*
Department of Anesthesiology and *First Department of Internal Medicine, Faculty of Medicine, Tottori University, Yonago 683, Japan
The sequential changes in the serum thyroxine (T4), triiodothyronine (T3), free T4 (FT4), free T3 (FT3), T4-binding globulin (TBG), thyrotropin (TSH) and cortisol concentrations, and T3-uptake (T3-U) value were studied in 10 patients during and after upper abdominal surgery under neuroleptanesthesia. Decreases in the serum T4, T3, FT3 concentrations and T3/T4 ratio, and increases in the T3-U value were observed after the induction of anesthesia, although no change in the serum TBG concentration was observed. At the same time, a slight but not significant increase in the serum FT4 level was observed after the induction of anesthesia. The serum TSH concentration decreased immediately after the induction of anesthesia, returned to the control level 30 min later, and then decreased again postoperatively. There was a significant correlation between the maximal decrease in serum TSH and the maximal increase in serum cortisol from control levels. Moreover, there was a significant correlation between the maximal decrease in TSH and the maximal decease in FT4 from control levels. These results suggest that premedication, general anesthesia and upper abdominal surgery directly and indirectly depress the tyroid gland while on the other hand the postoperative thyroid status is centrally suppressed.
Key words: neuroleptanesthesia; pituitary-thyroid function; upper abdominal surgery