Thyroid function and ioduria in infants after cardiac surgery: comparison of patients with primary and delayed sternal closure.

OBJECTIVES

Thyroid hormone alterations after cardiac surgery may be aggravated by the use of iodine antiseptics. We evaluated thyroid function and ioduria in infants with delayed sternal closure (DSC) who are exposed to povidone-iodine for sternal wound protection and compared them with findings in infants after primary sternal closure.

DESIGN

Prospective clinical study.

SETTING

Pediatric cardiac intensive care unit.

PATIENTS

Ninety-three infants after cardiac surgery using cardiopulmonary bypass, 60 of them with primary sternal closure and 33 of them with delayed sternal closure.

MEASUREMENTS AND MAIN RESULTS

Thyroid hormones were studied in patients with primary sternal closure immediately after surgery, 5 days and 19 days after surgery, in patients with DSC immediately after surgery, immediately after sternal closure, and 2 wks after sternal closure. Ioduria was evaluated on the first, third, and fifth postoperative days after cardiac surgery with primary sternal closure and immediately after DSC. In both groups of patients, low total triiodothyronine, total thyroxine, thyroxine-binding globulin levels, high reverse triiodothyronine levels, and normal free triiodothyronine, free thyroxine, and thyroid-stimulating hormone levels were recorded immediately after surgery. Concentrations of total triiodothyronine and thyroid-stimulating hormone were lower in the patients with DSC. Five days after primary sternal closure and 2 wks after DSC, all thyroid hormone levels were normal for age. Ioduria after DSC was higher than ioduria after primary sternal closure.

CONCLUSIONS

Patients with DSC compared with patients with primary sternal closure display more profound thyroid suppression in the immediate postoperative period. The use of povidone-iodine adhesive drapes with single povidone-iodine mediastinal irrigation in patients with DSC is associated with significant iodine absorption but no significant thyroid dysfunction.