the main goal of this study was to evaluate the possible effect of whole-body magnetic field(mf) exposure on the variations of corticosterone, free-t3, free-t4 and malonyl dialdehyde inplasma in 48 adult white new zealand male rabbits. animals were divided into six groups namely,c1 (normal diet, not exposed), c2 (normal diet, sham exposed), t1 (normal diet, exposed toelectromagnetic field), c3 ...

The contribution of L-thyroxine (T4) to nuclear thyroid receptor occupancy was studied in GC cells incubated with concentrations of 3,5,3'-triiodo-L-thyronine (T3) and T4 that resulted in free iodothyronine levels similar to those in serum of euthyroid rats. T4 accounted for 5.4-10% of the occupied receptors: T3 derived from T4 [T3(T4)] and T3 added to medium accounted for the remainder of rece...

Blind hamsters had no alteration of the dialyzable fraction of serum thyroxine (T4) but had depressed total and free T4 concentrations compared to controls. Prevention of the effects of blinding by pinealectomy indicates pineal influence on circulating free T4 concentration. Parallel changes in free T4 and the free T4 index indicate adequacy of the index in representing pineal-induced changes i...

We studied the dependence of the free thyroxin (T4) index and the ratio of T4 to thyroxin-binding globulin (TBG) on TBG concentrations, using sera from cases of congenital TBG deficiency and congenital TBG excess. Two such sera with similar concentrations of albumin, transthyretin, and free T4 were mixed to provide test samples with TBG concentrations covering the range of clinical interest wit...

Serum free thyroxin (FT4) was determined in 40 patients with various nonthyroidal illnesses. We studied seven methods: (1) a free thyroxin index calculated from total T4 and triiodothyronine resin uptake; (2) a free T4 index determined by enzyme inhibitor assays (Abbott's "Tetrazyme" and "Thyrozyme"); (3) a free T4 index calculated from total T4 and thyroxin-binding globulin; (4) free T4 by equ...

Objective: The aim of the present study was to compare the effects of Portulaca oleracea (Po) seeds extract and those of valsartan on cardiac function in levothyroxine (T4)-treated rats. Materials and Methods: Forty Wistar rats were divided into four groups (n=10): control, levothyroxine (T4), T4 plus valsartan (T4-Val) and T4 plus hydro-alcoholic extract of the P. oleracea seeds (T4-Po). Contr...

We have assessed the influence of albumin-bound thyroxin (T4) on apparent free T4 values obtained by two "unbound analog" free T4 methods (AmerlexR Free T4 and Clinical Assays one-step Free T4). We evaluated sera showing three different albumin anomalies: total hereditary analbuminemia, partially corrected analbuminemia, and familial dysalbuminemic hyperthyroxinemia, where abnormal albumin-bind...

UNLABELLED The standard treatment of hypothyroidism (central and primary) consists of thyroxine (T4) administration alone. However, the normal thyroid gland produces a small proportion of triiodothyronine (T3) directly into the circulation. AIM We aimed to study the free T3 to free T4 ratio in treated central hypothyroidism compared with euthyroidism and treated primary hypothyroidism. METH...

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...

There have been, and continue to be, reports of discordant free thyroxine (T4) 3 measurements when different free-T4 methods are applied to the same serum samples (1– 4 ). Our laboratory has attempted to identify some of the factors that contribute to these disparities. There are 4 separate components of serum T4: free T4, albumin-bound T4, transthyretin-bound T4, and thyroxine-binding globulin...