The nervous system is dependent upon thyroid hormones for normal development, and we previously reported that developmental Aroclor 1254 (A1254) exposure caused hypothyroxinemia, hearing loss and other behavioral changes in rats. (Goldey et al., 1995a; Herr et al., 1996). The hypothesis that A1254-induced hypothyroxinemia may have contributed to the observed functional changes was tested in pri...

BACKGROUND A recent randomized controlled trial suggests that hypothyroid subjects may find levothyroxine (l-T4) and levotriiodothyronine combination therapy to be superior to l-T4 monotherapy in terms of quality of life, suggesting that the brain registered increased T3 availability during the combination therapy. HYPOTHESIS Peripheral tissue might also be stimulated during T4/T3 combination...

1Department of Chemistry, Rutgers University, Camden, NJ, USA; Center for Computational and Integrative Biology, Rutgers University, Camden, NJ, USA 2Johns Hopkins Bloomberg School of Public Health, Center for Alternatives to Animal Testing (CAAT), Baltimore, MD, USA 3National Toxicology Program Interagency Center for the Evaluation of Alternative Toxicological Methods, National Institute of En...

We have identified an individual whose thyroxine (T4) concentration was undetectable with Abbott's fluorescence polarization immunoassay (FPIA) but within the reference range by radioimmunoassay or EMIT (Syva). The patient's thyrotropin, triiodothyronine, and T-uptake values were within the normal range. The T4 concentration measured by FPIA increased to normal when the immunoglobulin fraction ...

To investigate the role of thyroxine-binding globulin (TBG) and albumin in the availability of thyroid hormones to peripheral tissues, comprehensive kinetic studies of thyroxine (T4) and triiodothyronine (T3) were carried out in eight subjects with familial dysalbuminemic hyperthyroxinemia (FDH), in four subjects with inherited TBG excess, and in 15 normals. In high-TBG subjects, the reduction ...

Some equilibrium dialysis determinations of free thyroxine (T4) vary directly with thyroxine-binding globulin (TBG) concentration. This apparent TBG dependence has been limited to methods involving radiolabeled T4 added to the dialysis system (tracer dialysis). In this study we compared tracer dialysis with direct dialysis for determining free T4 and obtained the following results (mean +/- SD)...

We have studied whether, or not, tissue-specific regulatory mechanisms provide normal 3,5,3'-triiodothyronine (T3) concentrations simultaneously in all tissues of a hypothyroid animal receiving thyroxine (T4), an assumption implicit in the replacement therapy of hypothyroid patients with T4 alone. Thyroidectomized rats were infused with placebo or 1 of 10 T4 doses (0.2-8.0 micrograms per 100 gr...