Although the normal thyroid gland secretes both levothyroxine (L-T4) and levotriiodothyronine (L-T3), normalization of serum TSH with L-T4-replacement therapy alone in hypothyroidism is generally believed to result in a normal serum L-T3 and to reflect a euthyroid state. However several recent studies suggest that this may not be the case. Accordingly, the relationship between serum free L-T4 a...

BACKGROUND Thyroid is one of the ductless endocrine gland, which is located immediately below the larynx on either side of and anterior to the trachea. The principal hormones of thyroid gland are thyroxine (T4) and triiodothyronine (T3). The current study was carried out to investigate the impact of race, gender and area on the levels of Thyroxine (T4), Triiodothyronine (T3) and Thyroid Stimula...

A 34-year-old woman suffered from palpitation, easy sweating, heat intolerance, increased appetite, irregular menstrual cycle and hand tremor for 1 year. Thyroid function tests showed elevated serum thyroxine (T4), tri-iodothyronine (T3) and thyrotropin (TSH). Computerized tomography (CT) revealed pituitary tumor with supraseller extension. Thyrotropin releasing hormone (TRH) test showed blunte...

T3 or iodide, at the concentration of 10- minus 3M, inhibits TSH- or dibutyryl-cyclic AMP-induced thyroidal intracellular colloid droplet formation, while leaving the TSH-induced increase in cyclic AMP levels intact. The effect of T3 appeared not to be mediated through the iodide derived from deiodination of T3. Those results clearly demonstrate that T3 or iodide acts at the point beyond cyclic...

One hundred and forty seven clinically proven hyperthyroid subjects were studied using radioimmunoassay techniques for the estimation of serum thyroid hormones and pituitaryTSH concentrations. In females toxic goitre was more frequently seen in the age group 21 to 30 years and in males 31 to 40 years. The mean levels for serum T4, T3, FT4 and FT1 were significantly elevated while the mean level...

Serum concentrations of thyroxine (T4), triiodothyronine (T3) and Thyroid Stimulating Hormone (TSH) are used to assess thyroid function. It is recommended that each laboratory or hospital should establish its own reference values of T4, T3 and TSH for their clients because these hormones vary with ethnicity, geographical and climatic conditions of a population. There is no documented study whic...

In euthyroid sick syndrome [non-thyroidal illness (NTI)], a number of investigators have described TSH and serum thyroid hormone abnormalities, low T3, low T3 and T4, increased T4, low TSH, etc. Those cases of NTI where there is only T3 decrease [and normal serum T4, free T4 (FT4), and TSH levels] are specifically referred to as low T3 syndrome. However, the information in regard to low T3 synd...