RESUMO
OBJECTIVE: The aim of this prospective study was to examine whether providone-iodine used for sternal wound protection in infants with delayed sternal closure (DSC) influences the thyroid function. PATIENTS AND METHODS: Thyroid hormones (see bellow) and thyroxine binding globulin (TBG) were estimated by radioimmunoassay and ioduria by mass spectrometry in 20 infants in whom cutaneous povidone-iodine was continuously applied on the skin for 1-7 days before DSC after open heart surgery. RESULTS: In the early postoperative period the median levels of total triiodothyronine (TT3), total thyroxine (TT4) and thyroxine-binding globulin (TBG) were below the lower limit of normal, while these of reverse triiodothyronine (rT3) were above normal. The median levels of free triiodothyronine (FT3), free thyroxine (FT4), and thyroid stimulating hormone (TSH) were normal. Two weeks after the sternal closure, the levels of TT3, TT4 and TBG increased significantly (P < 0.001), while these of rT3 decreased, but not significantly. The levels of TSH increased (P < 0.001), being above normal in 7 patients. Four weeks after the sternal closure, TSH levels remained markedly increased in 4 infants. These patients were considered to be hypothyroid and were started on thyroxine replacement therapy. Such replacement treatment was withdrawn at a median age of 6.5 months (range 5-8 months). Urinary iodine concentration on the last day of povidone-iodine exposure was several times higher (P < 0.001) than that in the control group of healthy infants. CONCLUSIONS: Transient hypothyroidism was found in four of 20 infants with DSC who were exposed to povidone-iodine. It is suggested to monitor TSH level in these patients, optimally at 4 weeks after closure of the sternum, when findings may show true hypothyroidism.
