NEW YORK (Reuters Health) – Major surgery often leads to transient thyroid hormone derangements. When it does, short-duration T3 therapy has no apparent benefit, according to a new systematic review.
In fact, thyroid hormone treatment in those cases may be harmful, the researchers reported online July 28th in The Journal of Clinical Endocrinology & Metabolism.
“T3 therapy given in the postoperative period did not show a beneficial effect but may induce hyperthyroidism,” Dr. Elaine M. Kaptein from University of Southern California, Los Angeles, told Reuters Health by e-mail.
In light of ongoing controversy surrounding thyroid hormone replacement for patients with decreased postoperative T3 levels, Dr. Kaptein and colleagues analyzed 14 randomized controlled studies of the effect of thyroid hormone therapy after cardiac (13 trials) or renal (one trial) surgery. In no case did patients have primary hypothalamic, pituitary, or thyroid diseases.
Four studies showed significantly higher cardiac index among patients who received high intravenous doses of T3 six hours after surgery, and three studies showed similar benefits on cardiac output of low intravenous doses of T3 four to six hours after surgery. Quality was only low to moderate in these studies.
The remaining studies yielded inconclusive results for systemic vascular resistance, heart rate, pulmonary capillary wedge pressure, new-onset postoperative atrial fibrillation, and inotrope use, and there was no difference in hospital mortality in four studies that investigated high-dose intravenous T3 administration.
“All comparisons suffered from the small number of studies (no more than four studies in a comparison), many comparisons also suffered from the small number of study subjects, and one comparison suffered from imprecise data,” the researchers note.
Effects of T3 administration on serum TSH levels and T4 levels varied from study to study and between intravenous and oral administration. However, TSH was significantly decreased with T3 therapy in two studies.
“Because studies only included patients after coronary artery bypass graft or valve surgery (13 studies) or after renal transplantation (one study),” the investigators say, “findings may not be generalizable to other patient populations.”
“If T3 therapy is considered as a treatment to increase cardiac output, the side effects of T3 therapy have to be evaluated more carefully and the cardiac effects evaluated,” Dr. Kaptein said.
Thyroid Hormone Therapy for Postoperative Nonthyroidal Illnesses: A Systematic Review and Synthesis
J Clin Endocrin Metab 2010.