Perioperative thyroid hormone kinetics in patients undergoing major oral and maxillofacial operations

The aim of this study was to investigate the perioperative response of serum thyroid hormones in patients who underwent extensive maxillofacial operations with desflurane (0.2 to 1.5 MAC) and remifentanil (0.05 to 0.3 microg/kg/min) anesthesia.

Serum thyroxine, total and free triiodothyronine, thyroid-stimulating hormone, interleukin-1beta and 6, TNF-alpha, free fatty acids, S100B protein, CRP, as well as amyloid A protein were measured in 13 patients subjected to extensive oral and maxillofacial operations. Samples were collected before anesthesia induction, at the end, and 6, 12, 24, and 72 hours after the end of surgery. Patients during the study fasted, and at the postoperative period received Ringer's saline or with 5% dextrose alternatively, at the rate of 0.5 to 1.5 mL/kg/hr.

Thyroid hormones concentrations showed a significant decrease over time whereas their values recovered to the baseline 72 hours after surgery. Interleukin 1beta, 6, S100B protein, CRP, serum amyloid A protein, and free fatty acids showed a significant increase 6, 12, and 24 hours after the end of the operation as related to the basal value. No significant clinical complications were recorded over the study.

Patients undergoing extensive oral and maxillofacial surgery exhibit marked decrease in serum thyroid hormones. Stress response, anesthesia, and perioperative fasting may be decisive factors eliciting this response. These metabolic derangements do not deteriorate the clinical outcome and subsequently may be an adaptive response for energy preservation in various organs.