to produce the thyroid hormones T3 and T4, which regulate gene transcription throughout the body (1). In medical practice, the thyroid becomes an issue when its size or shape becomes abnormal or when it produces too much or too little hormone. Thus, we typically think of the thyroid with reference to the clinical states of goiter, or hyper-or hypothy-roidism. But what is the physiology of the t...

The importance of thyroid hormones during brain development has been appreciated for many decades. In humans, low levels of circulating maternal thyroid hormones, e.g., caused by maternal hypothyroidism or lack of iodine in diet, results in a wide spectrum of severe neurological defects, including neurological cretinism characterized by profound neurologic impairment and mental retardation, und...

Thyroid hormones are essential for normal brain development in vertebrates. In humans, abnormal maternal thyroid hormone levels during early pregnancy are associated with decreased offspring IQ and modified brain structure. As numerous environmental chemicals disrupt thyroid hormone signalling, we questioned whether exposure to ubiquitous chemicals affects thyroid hormone responses during early...

All symptoms and most objectively verified abnormalities among fibromyalgia (FMS) patients are characteristic of subsets of patients with hypothyroidism or partial peripheral thyroid hormone resistance. Laboratory tests have shown a higher-than-normal incidence of thyroid disease among FMS patients. Among 40 objectively verified abnormalities that also occur in hypothyroidism and peripheral thy...

Hypothyroidism is a common endocrine disorder resulting from deficiency of thyroid hormone or its effects on peripheral tissues. It usually is caused by an insufficient production of thyroid hormone by thyroid gland (primary hypothyroidism), but it could be also caused by inadequate secretion of either thyrotropin (ie. thyroid-stimulating hormoneTSH) from the pituitary gland (secondary hypothyr...

A normal pregnancy results in a number of important physiological and hormonal changes that alter thyroid function. These changes mean that laboratory tests of thyroid function must be interpreted with caution during pregnancy. Levels of thyroxine binding globulin (TBG) and production of T3 and T4 hormones and the daily requirement of iodine in pregnancy are increased to 50%, TSH receptor stimu...

We have recently shown that a thyroid hormone-responsive transcription stimulatory element exists in the 5'-flanking DNA near the rat growth hormone (rGH) gene (Crew, M. D., and Spindler, S. R. (1986) J. Biol. Chem. 261, 5018-5022). Progressive deletion-transfection analysis of the 5' end of the gene has led to the identification of two genetic elements responsive to thyroid hormone. The first ...

The liver is an important target organ of thyroid hormone. However, only a limited number of hepatic target genes have been identified, and little is known about the pattern of their regulation by thyroid hormone. We used a quantitative fluorescent cDNA microarray to identify novel hepatic genes regulated by thyroid hormone. Fluorescent-labeled cDNA prepared from hepatic RNA of T3-treated and h...

Thyroid hormone metabolism and action are largely intracellular events that require transport of iodothyronines across the plasma membrane. It has been assumed for a long time that this occurs by passive diffusion, but it has become increasingly clear that cellular uptake and efflux of thyroid hormone is mediated by transporter proteins. Recently, several active and specific thyroid hormone tra...

Graves's disease (diffuse toxic goitre) Toxic nodular goitre Multinodular (Plummer's disease) Uninodular (toxic adenoma) Nodular goitre with Graves's disease Excess thyroid stimulating hormone Pituitary tumour Choriocarcinoma and hydatidiform mole Embryonal testicular carcinoma Other malignancy (?) Extraneous thyroid hormone Exogenous: Intentional factitious Overenthusiastic therapy During T-3 ...