Active and inactive thyroid hormone levels in elective and acute surgery.

Area of Science:

• Endocrinology
• Surgical Physiology

Background:

• Thyroid hormones, including thyroxine (T4), triiodothyronine (T3), and reverse T3 (rT3), play crucial roles in metabolism.
• Surgical stress can significantly impact endocrine function and metabolic status.

Purpose of the Study:

• To investigate the dynamic changes in thyroid hormones (TSH, T4, T3, rT3) and cortisol levels in patients undergoing surgery.
• To differentiate hormonal responses between elective surgery and acute peritonitis.

Main Methods:

• Blood samples were collected from patients undergoing elective cholecystectomy (n=10) or acute laparotomy for peritonitis (n=11).
• Plasma concentrations of TSH, T4, T3, rT3, and cortisol were measured.
• Hormonal changes were analyzed in relation to anesthesia, surgical procedure, and postoperative recovery.

Main Results:

• Thyroid-stimulating hormone (TSH) and thyroxine (T4) levels remained largely unchanged.
• Triiodothyronine (T3) levels decreased during and after surgery in both groups, with pre-existing reduction in the peritonitis group.
• Reverse T3 (rT3) levels showed an inverse pattern to T3, increasing during the perioperative period.
• Cortisol levels increased preceding the alterations in T3 and rT3.
• Hormone levels normalized with patient recovery and resumption of oral nutrition.

Conclusions:

• Elective and acute surgery induce a transient reduction in extrathyroidal T3 production and a reciprocal increase in rT3.
• This metabolic adaptation may be linked to adrenocortical activation and altered nutritional status.
• The precise mechanisms underlying these surgical-induced thyroid hormone changes require further investigation.