Context l-Thyroxine (l-T4) therapy of central hypothyroidism (CH) is guided by measurements of serum free thyroxine (FT4), which should be above the midnormal range value (MNRV). In some countries, novel formulations of oral l-T4 (liquid or softgel) are available further to the classic tablets. The intestinal absorption of either novel formulation is greater than tablets in patients with primar...

Lin, Hung-Yun, Paul M. Yen, Faith B. Davis, and Paul J. Davis. Protein synthesis-dependent potentiation by thyroxine of antiviral activity of interferon-g. Am. J. Physiol. 273 (Cell Physiol. 42): C1225–C1232, 1997.—We have studied the prenuclear signal transduction pathway by which thyroid hormone potentiates the antiviral activity of human interferon-g (IFN-g) in HeLa cells, which are deficien...

Excessive bias and imprecision are major analytical problems associated with some assays for free and total thyroxine (T4). Bias in free T4 methods is largely proportional to variations in serum T4 binding. In direct methods, this is attributable to requirements for substantial quantities of protein-bound T4 to replace analytical losses of free T4. In some total T4 methods, bias is inversely pr...

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 ...

THE measurement of serum free thyroxine (FT4), which forms a small fraction (0.01-0.05 per cent) of the circulating total thyroxine (TT4), might be expected to provide the most accurate single biochemical index of thyroid status, on the basis that only free hormone is bioavailable. The conventional estimation of FT4 by equilibrium dialysis' is time consuming and the arrival of radioimmunoassay ...

We evaluated the effect of hapten heterology on free thyroxine (FT4) immunoassays involving the biotin-streptavidin system and time-resolved fluorometry. We compared protein derivatives of thyroxine (T4) and triiodothyronine (T3) as solid-phase antigen or biotinylated protein-tracer conjugate for competitive (or sequential) binding to a mouse anti-T4 monoclonal antibody. In both one- and two-st...

BACKGROUND Thyroid is one of the ductless endocrine gland, which is located immediately below the larynx on either side of and anterior to the trachea. The principal hormones of thyroid gland are thyroxine (T4) and triiodothyronine (T3). The current study was carried out to investigate the impact of race, gender and area on the levels of Thyroxine (T4), Triiodothyronine (T3) and Thyroid Stimula...

UNLABELLED In order to examine the significance of differences in the triiodothyronine/thyroxine (T3/T4) ratio in the achievement of euthyroidism and in different thyroidal diseases, we studied 1050 subjects: 233 were euthyroid (Eu), 239 hypothyroid (Hypo) with initial TSH levels >15 mU/L, 273 hypothyroid on substitution therapy with L-thyroxine alone and TSH values of 0.35-3.5 mU/L, (hypoRx), ...

Thyroid hormones exert a profound effect on development, growth, and metabolism of skeleton. In the present study, we evaluated the effects of thyroxine (T4) and growth hormone (GH) on the terminal differentiation of rib growth plate chondrocytes in three-dimensional pellet culture. T4 (30ng/ml) stimulated the expressions of type II and X collagens, alkaline phosphatase (ALP) activity. On the o...

We report that aurone derivatives of plant extracts produce potent, dose-dependent, and ultimately complete inhibition of three different metabolic monodeiodination pathways catalyzed by rat liver microsomal type I iodothyronine deiodinase. These data show that (3'),4',4,6-(tetra)trihydroxyaurones are the most potent naturally occurring plant-derived inhibitors of this deiodinase enzyme (IC50 V...