LEVOTHYROXINE PHARMACOKINETICS

这个子项目是众多研究子项目之一

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This study, funded by the Obstetrics and Pharmacology Research Unit of NlCHD, is a prospective, multi-center, open-label, non-randomized, pharmacokinetic study before pregnancy, during pregnancy and the postpartum period. Pharmacokinetics of levothyroxine (LT4) will be conducted in supplemented hypothyroid non-pregnant and pregnant women. Synthetic levothyroxine sodium (LT4) supplementation may need to be increased throughout pregnancy. Since Thyroid Hormone concentration increases by approximately 50% by Gestational Week 6 it is thought that supplementation should be increased by at least 50%. However, little is known regarding the appropriate LT4 dosing in pregnancy, and whether dosing should change throughout the different stages of gestation to optimize efficacy. Secondly, the minimal LT4 supplementation needed to prevent adverse neuro-developmental effects in the fetus is not known. The PIs propose to investigate LT4 single dose pharmacokinetics using stable isotope methodology. Women participating in this study will continue on their normal medication. They will also be given a special marker called a "stable isotope" so that the study team can follow fevothyroxine supplementation. The stable isotope will be given only once during the pre-pregnancy {or post-partum) visit and once during the pregnancy visit. Stable isotopes have no harmful or radiation effects; tests have shown them to be safe in newborn infants and they have been used for over 20 years in studies