Pharmacokinetic evaluation of triiodothyronine supplementation in children after modified Fontan procedure

Abstract

Background - Triiodothyronine (T3) supplementation may be a useful adjunct in the management of patients after cardiopulmonary bypass. Limited data are available regarding the use and pharmacokinetics of T3 in children. The present study was performed to evaluate T3 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 T3 at dosages of 0.4, 0.6, and 0.8 μg/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 T3 level was 316±67 pg/dL after then administration of a placebo. Patients who received T3 had mean peak free T3 levels of 972±88, 1351±299, and 1869±281 pg/dL for the dosages of 0.4, 0.6, and 0.8 μg/kg, respectively. The calculated half-life of T3 was 7 hours. Conclusions - The half-life of intravenous T3 in children is approximately one-third of that reported for adults. These results provide a framework for studying the efficacy of T3 supplementation in children undergoing open-heart surgery.