The present study was undertaken to study the binding of several thyroid hormones and structurally related compounds to human serum thyroxine-binding alpha-globulin (TBG). The source of TBG was normal human serum diluted 1:100 in 0.035 M barbital buffer, pH 7.4. In the binding assays, 125I-thyroxine, unlabeled thyroxine, and diluted serum were incubated for 20 h at 37 degrees in Plexiglas equil...

We have investigated the clinical utility of two direct radioimmunoassays for free thyroxin, an enzyme-inhibition immunoassay, and a direct measurement of thyroxin-binding globulin (TBG) by radioassay. All assay methods correctly identified greater than or equal to 90% of euthyroid, hyperthyroid, and hypothyroid patients who had normal TBG concentrations. In patients with altered TBG concentrat...

We studied the correlation of thyroxin (T4)-binding proteins with the apparent free T4 (FT4) in 101 patients with nonthyroidal illness (NTI). Most patients (95%) were seriously ill at the time of blood collection. Concentrations of T4-binding prealbumin (transthyretin), albumin, and T4-binding globulin (TBG) often were low in the sera of these patients. Albumin was the most frequently subnormal...

Inherited thyroxine binding globulin (TBG) disorder can be identified incidentally or through neonatal screening test. TBG excess is characterized by high levels of thyroxine (T4) but normal level of free T4 (fT4), while TBG deficiency presents with low T4 levels and normal fT4 levels. A 27-day-old newborn was brought to the hospital because of hyperthyroxinemia detected by neonatal screening. ...

Thyroxine-binding globulin (TBG) assays by the polyacrylamide electrophoresis assay of Nikolai and Seal have been carried out on 315 normal subjects. The assay was carried out with 200 exogenous labeled thyroxine per 100 ml added to the samples. The means and standard deviations for the three thyroxine-binding proteins in males (n = 140) were: TBG 19.7 ±3.0 p.g/100 ml, thyroxine-binding albumin...

The secondary and tertiary structure of human plasma thyroxine-binding globulin (TBG) was investigated by circular dichroism and fluorescence properties. The relaxation time of TBG indicated that it is a compact, symmetric molecule. It was calculated from the far ultraviolet CD spectrum that about one-half of the peptide groups are equally distributed in alpha helical and beta structures. In th...

CONTEXT The hormonal factors involved in the regulation of peak bone mass (PBM) in men have not been fully investigated. Apart from gonadal steroids and somatotropic hormones, thyroid hormones are known to affect bone maturation and homeostasis and are additional candidate determinants of adult bone mass. OBJECTIVE We aimed to investigate between-subject physiological variation in free and to...

Free thyroxin (FT4) concentrations, total thyroxin/thyroxin-binding globulin (T4/TBG) ratios, and thyrotropin (TSH) and albumin concentrations were measured in serum in a longitudinal study in each of the three trimesters of 25 normal pregnancies. In late pregnancy, FT4 estimates by assays reputedly either affected or unaffected by albumin were in the lower half of the reference range for nonpr...

In this automated apoenzyme reactivation immunoassay system (Ames Optimate’”)forthyroxin-binding globulin (TBG),thesampleand M-aminohexylflavin adeninedinucleotide-labeled TBG reactsequentially withantiserum. Then apoglucose oxidaseis added to combine with the free fraction and generate glucose oxidase activity, which is measured colorimetrically. The assay requires 100 .tLof sample and covers ...