We studied the effect of thyroid hormone administration on responsivity of murine thyroid to exogenous thyrotropin (TSH) in order to explore the possibility that the thyroid gland might be directly inhibited by its own hormones. In the rat both L-thyroxine (T4) and 3,5,3'-L-triiodothyronine (T3) pretreatment inhibited TSH-induced thyroidal ornithine decarboxylase (ODC) activity in vivo in a dos...

We have studied the effect of two protein phosphatase inhibitors on thyrotropin (TSH)-stimulated triiodothyronine (T3) production by sheep thyroid cells grown in primary culture. Incubation of sheep thyrocytes with okadaic acid (OA) and calyculin-A (CL-A), two potent inhibitors of type 1 (PP1) and type 2A (PP2A) protein phosphatases, resulted in an increase of TSH-stimulated T3 production. This...

The changes in plasma thyroid hormone concentration were studied during exchange transfusion performed for haemolytic disease. 24 transfusions were performed using blood preserved with acid-citrate and dextrose and in 11 cases 10 or 50 mug glucagon was added to the donor blood. Plasma tri-iodothyronine (T3), thyroxine (T4), thyrotropin (TSH), thyroid hormone binding capacity, and free thyroxine...

The Thyroid Status was studied by estimating the total serum levels of T3 and T4 by radioimmunoassay (RIA) and TSH by radioimmunometric Assay (IRMA) from 635 school children (8-20 years; male 129, female 506) of the Dibrugarh district: a chronic endemic goitrous region of India. The results were compared with the control group of 147 (male 48, female 99) of healthy medical students of the same ...

We have previously shown that sera from many hypothyroid patients stimulated adenylate cyclase activity as measured by serum bioactive TSH concentrations produced by FRTL-5 cell line. This TSH-stimulating activity did not correlate with serum immunoreactive TSH. IgG fractions of these sera did not stimulate FRTL-5 cells. The present study was, therefore, undertaken to investigate the thyroid st...

A cross-sectional study of thyrotropin (TSH), thyroxine (T4) and triiodothyronine (T3) in human serum was performed aiming to define their normal values. In total, 201 assays were performed on 70 normal individuals, 26 men and 44 women, with ages ranging from 2 to 84 years. Serum TSH was measured with a highly sensitive immunoradiometric assay (IRMA) kit and T4 & T3 were determined with commerc...

Background: Since the introduction of the first radioimmunoassay, several improvements have been made in the design of immunoassays such as method of antibody production, labeling, automation and detection technology. We performed an analytical evaluation of the new electrochemiluminescent immunoassay (ECLIA) for serum TSH, FT4 and T3 in the Elecsys 2010 immunoassay system and compared the resu...

In order to investigate the effect of 3,5,3'L-triiodothyronine (T3) administration on thyroid hormone concentrations in serum, thyroxine (T4), T3, 3,3',5'L-triiodothyronine (reverse T3, rT3) and thyroid stimulating hormone (TSH) concentrations in serum were determined before and after T3 administration in 10 hypothyroid patients maintained on constant doses of T4. Ten hypothyroid patients given...

Thyroid hormones, T4 and T3, regulate their own production by feedback inhibition of TSH and TRH synthesis in the pituitary and hypothalamus when T3 binds to thyroid hormone receptors (TRs) that interact with the promoters of the genes for the TSH subunit and TRH. All TR isoforms are believed to be involved in the regulation of this endocrine axis, as evidenced by the massive dysregulation of T...