Thyroid function in infants following cardiac surgery: comparative effects of iodinated and noniodinated topical...

Cardiopulmonary bypass has profound effects on thyroid hormone metabolism. These effects may be exacerbated in infants because they are able to absorb large quantities of iodine transcutaneously. The purpose of this study was to test the hypothesis that preoperative povidone-iodine contributes to postoperative thyroid depression in infants who undergo cardiac surgery.

Prospective, randomized, controlled trial.

Children's Hospital and Medical Center, Seattle, WA.

Thirty-seven infants undergoing repair of congenital cardiac defects.

Infants requiring cardiopulmonary bypass were divided into two groups: Group 1 received povidone-iodine; group 2 received chlorhexidine as a topical preoperative antiseptic. Group 3 did not require cardiopulmonary bypass for repair of cardiac defects and received povidone-iodine as a preoperative antiseptic.

Thyrotropin (TSH), total triiodothyronine (T3), and thyroxine (T4) were measured at four intervals: a) before preparation for surgery; b) immediately after surgery; c) at 2 days after surgery; and d) at 5 to 8 days after surgery. There was a significant decrease in TSH concentrations immediately after surgery in the two bypass groups. This change was significantly greater than in the change in TSH concentration in the thoracotomy group. Total T3 and T4 concentrations decreased by postoperative day 2 in both groups 1 and 2, and the changes were significant compared with group 3. Total T3 and T4 concentrations increased significantly in all groups after postoperative day 2, with no significant difference between the three groups.

Cardiopulmonary bypass has a more significant effect on thyroid hormone metabolism than does the preoperative antiseptic.