Pharmacokinetic evaluation of triiodothyronine supplementation in children after modified Fontan procedure

Background-Triiodothyronine (T-3) supplementation may be a useful adjunct in the management of patients after cardiopulmonary bypass. Limited data are available regarding the use and pharmacokinetics of T-3 in children. The present study was performed to evaluate T-3 pharmacokinetics in a cohort of children undergoing the modified Fontan procedure. Methods and Results-A total of 28 patients were enrolled in this randomized, prospective study. The patients were divided into 4 groups: 1 group received a placebo and 3 groups received intravenous T-3 at dosages of 0.4, 0.6, and 0.8 mu g/kg, respectively. All 28 patients survived their operative procedures. Two patients developed low cardiac output, and 3 patients had pleural effusions. The median length of hospital stay was 7 days. The mean free T-3 level was 316+/-67 pg/dL after then administration of a placebo. Patients who received T-3 had mean peak free T-3 levels of 972+/-88, 1351+/-299, and 1869+/-281 pg/dL for the dosages of 0.4, 0.6, and 0.8 mu g/kg, respectively, The calculated half-life of T-3 was 7 hours. Conclusions-The half-life of intravenous T-3 in children is approximately one-third of that reported for adults, These results provide a framework for studying the efficacy of T-3 supplementation in children undergoing open-heart surgery.