What is the role of surgery in the development of euthyroid sick syndrome?

Updated: Aug 28, 2020
  • Author: Serhat Aytug, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Total T3 falls dramatically on the day of surgery and remains significantly decreased postoperatively. The degree of the fall is related to the severity of surgical trauma. An absolute percent increase of free T3 also occurs on the day of the surgery. The free T3 concentration rapidly falls to low levels postoperatively, paralleling the decline in total T3. T4 usually is not altered on the day of surgery. One study demonstrated that total T4 decreased during surgery with epidural anesthesia but increased with general anesthesia. The percent of free T4 increases during surgery and decreases postoperatively.

TSH has been found to be unchanged during surgery, except with hypothermic surgery, where TSH increased. In a 2001 study by Michalaki, in patients who underwent abdominal surgery, the decline of serum T3 was not correlated with the increase of serum IL-6 or TNF-alpha levels; rather, brisk cortisol response to surgery was postulated to explain, in part, the early decrease in serum T3 levels in sick euthyroid syndrome. [21]

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