Iodine is a micronutrient essential for the synthesis of thyroid hormones1. The thyroid gland takes iodine from the diet, stores it and subsequently incorporates it into other molecules, to produce two types of thyroid hormones as a final product: triiodothyronine (T3) and thyroxine (T4) containing three and four iodine atoms respectively. Both circulate in blood bound to proteins and act on sp...

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...

Market-size (61-68 day-old) AA broiler chickens were exposed to simulated high-cyclic summer temperatures of North, Central and South China for 5 continuous days. Blood samples were collected at 0AM, 4AM, 8AM, 0PM, 4PM and 8PM each day, and concentrations of triiodothyronine (T3) and thyroxine (T4) were determined by double-antibody radioimmunoassay (RIA). T3, T4 concentration and T3/T4 ratio h...

The present opinions on the therapy with L-thyroxine (L-T4) of non-toxic multinodular, as well as of non-toxic thyroid nodules are rather divergent. This treatment is based on the suppression of TSH secretion from the pitu-

In 327 newborns cord blood thyroxine (T4) was 11.8 +/- 0.4 mug/100 ml (SEM) (151.9 +/- 5.1 nmol/l), and serum thyrotrophin (TSH) 6.7+/-1.0 muU/ml. Variability was marked for both T4 and TSH. Remeasured in the same patients on the fifth day of life, the TSH level was 3.7 +/- 1.0 muU/ml, lower than at birth (P less than 0.001), while scattering of TSH values was much smaller, with 99.4 % of value...

OBJECTIVE Subclinical hypothyroidism (SCH) and its associations with atherosclerosis (AS) and cardiovascular disease remain controversial. The purpose of our study was to observe changes in endothelial functioning and hemodynamics in rats with SCH and to determine whether L-thyroxine (L-T4) administration affects these changes. METHODS In total, sixty male Wistar rats were randomly divided in...

introduction: neuropeptide y (npy) is the most abundant peptide present in mammals' brains. the majority of npy-producing neurons is in arcuate and paraventricular nuclei of hypothalamus which affect hypophysiotrapic factors secretion. in this study we investigated the effect of intravenous injections of various doses of npy on thyroxine (t4) and triiodothyronine (t3) serum concentrations....

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. ...

The Tasmanian bettong (Bettongia gaimardi) is a small rat-kangaroo (marsupial) found only in Tasmania, Australia. The duration of pouch life is 15 weeks. Adults and older young display non-shivering thermogenesis and this paper examines the role of thyroxine in the development of endothermy in pouch young. Free thyroxine (T4) concentrations varied throughout pouch life. The mean (+/-SE) concent...

PURPOSE Opaque chick corneas become thin and transparent from embryonic day (E)9 to E20 of incubation. Thyroxine (T4) injected in ovo on E9 induces precocious transparency by E12. The present study was conducted to determine whether corneal cells differentially express genes for T4 regulation, keratan sulfate proteoglycan (KSPG) synthesis, crystallins, and endothelial cell ion transporters duri...