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...

• Explain how inappropriate (normal or increased) thyrotropin (TSH) secretion in the presence of hyperthyroidism can be a clue to a thyrotropin adenoma of the pituitary. • Describe the clinical and endocrinological features of thyrotroph pituitary adenoma and how to distinguish it from other states of inappropriate TSH secretion. • Define the roles of pituitary surgery, radiotherapy, and drug t...

The thyrotropin-releasing hormone receptor from rat brain was solubilized in a stable unbound form. The natural glycoside digitonin was the only detergent of a variety tested capable of solubilizing the active receptor. The digitonin-solubilized receptor exhibited binding kinetics for 3-[3H]methylhistidine thyrotropin-releasing hormone virtually identical to membrane preparations and responded ...

The introduction of sensitive thyrotropin assays and free thyroid hormone measurements has simplified the interpretation of thyroid function tests. However, important pitfalls and difficult cases still exist. In this review, thyroid function test results are grouped into six different patterns. We propose that if assays for thyrotropin, free T3, and free T4 are all done, knowledge of these patt...

resistance to thyroid hormone is an uncommon condition. we report the clinical and laboratory findings of a case with both resistance to thyroid hormone and, a reduced capacity to produce and respond to thyroid hormone. rth is a disorder characterized by elevated circulating thyroid hormones, state of non-suppressed pituitary tsh secretion and refractoriness to hormone action in peripheral tiss...

Resistance to thyroid hormone (RTH) coexisting with ectopic thyroid is rare. Here we report a case of RTH with ectopic thyroid. A ten-year-old girl had been misdiagnosed as congenital hypothyroidism and treated with levothyroxine since she was born. Ten-year follow-up showed that the elevated thyrotropin was never suppressed by levothyroxine and no signs indicating hyperthyroidism or hypothyroi...