Blood was taken from women in each trimester of pregnancy at routine antenatal visits. Further samples were collected from an age matched control group of euthyroid women taking no medication. Free triiodothyronine and free thyroxine concentrations were measured by direct radioimmunoassay (Amerlex Kit methods, Amersham International, Amersham, Buckinghamshire).2 These free hormone assays use th...

The strong affinity between thyroxine and the specific thyroxine-binding protein (TBP) of human serum (1) is apparent from, a) the inability to remove more than small amounts of thyroxine from the serum by prolonged dialysis (2), and b) the effectiveness with which TBP competes with albumin for available thyroxine in serum, despite its much smaller concentration. Thyroxine bound to TBP is, neve...

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....

Brien, T. G., Fay, J. A., and Griffin, E. A. (1974). Archives of Disease in Childhood, 49, 225. Thyroid status in the newborn infant: effective thyroxine ratio and free thyroxine index. The effective thyroxine ratio (ETR) was determined in 28 term and 17 premature infants at birth and in 17 infants aged 0 to 6 weeks. The mean values found were significantly higher than those in 20 adult euthyro...

We describe a method for directly measuring free thyroxine in human serum. Antibody to thyroxine was encapsulated within a semipermeable nylon membrane that excludes substances of relative molecular mass greater than 20,000. The microencapsulated antibody was then presaturated with [125I]thyroxine. Serum incubated with the microcapsules initiated a displacement reaction between free thyroxine a...

Thyroxine, the principal thyroid hormone, circulates in blood almost completely bound to carrier proteins. The main carrier is thyroxine-binding globulin (TBG). However, only the free (unbound) portion of thyroxine is responsible for the biological action. Further, the concentrations of the carrier proteins are altered in many clinical conditions, such as pregnancy. In normal thyroid function a...

Plasma thyroid stimulating hormone (TSH) concentrations obtained during the first four years of treatment in 418 children with congenital hypothyroidism, identified by neonatal screening, were examined in relation to paired measurements of plasma thyroxine (n = 1945), free thyroxine (n = 836), triiodothyronine (n = 480), and free triiodothyronine (n = 231), and estimated daily dose of thyroxine...

The activities of hexokinase, citrate-cleavage enzyme, ;malic enzyme' and NADP-linked isocitrate dehydrogenase have been measured in the adipose tissue, testes and adrenals of normal rats, hypophysectomized rats and hypophysectomized rats treated with either thyroxine or thyroxine plus luteinizing hormone. Hypophysectomy reduced the activity of all four enzymes in all three tissues. Thyroxine a...

Indices of thyroid function were measured in 97 preterm infants at birth and at 5, 10, and 15 days of age. Triiodothyronine uptake, free thyroxine index, thyroxine, free thyroxine, triiodothyronine, reverse triiodothyronine, and thyroxine binding globulin values at birth correlated with gestational age, whereas thyroid stimulating hormone values did not. Treatment with steroids prenatally had n...