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Liothyronine is the most potent form of thyroid hormone. Liothyronine sodium, a salt of triiodothyronine (T 3 ), is chemically similar and pharmacologically equivalent to T 3 . As such, it acts on the body to increase the basal metabolic rate, affect protein synthesis and increase the body's sensitivity to catecholamines (such as adrenaline) by ...
Hypothyroidism (also called underactive thyroid, low thyroid or hypothyreosis) is a disorder of the endocrine system in which the thyroid gland does not produce enough thyroid hormones. [3] It can cause a number of symptoms, such as poor ability to tolerate cold , extreme fatigue, muscle aches , constipation , slow heart rate , depression , and ...
Ions such as thiocyanate [7] (from cigarette smoking for example [8]) and perchlorate decrease iodide uptake by competitive inhibition and, as a consequence of reduced thyroxine and triiodothyronine secretion by the gland, cause, at low doses, an increased release of thyrotropin (by reduced negative feedback), which then stimulates the gland.
Thyroxine has a half-life of approximately one week and hence maintains relatively stable blood levels. Its production and release are controlled through a complex feedback loop involving the hypothalamus, pituitary gland, and thyroid gland. This regulatory system ensures that optimal hormone levels are maintained. [4]
They inhibit release of thyroid hormones by the thyroid gland.The most studied drug in this class is lithium, which inhibits thyroid hormone secretion by inhibiting iodotyrosine coupling, thyroidal iodide uptake, and alteration in structure of thyroglobulin, [10] a protein which acts as a substrate for the synthesis of thyroid hormones and storage of inactive forms of T3, T4 and iodine within ...
Fasting in healthy, euthyroid people causes reduced T3 and elevated rT3, although TSH is usually unchanged. [3] [5] [10] Even moderate weight loss can lower T3. [2] This may be primarily via reduced levels of leptin (the satisfaction hormone). Low leptin levels can downregulate hypothalamic TRH neurons and cause a reduction in TSH.
Low-T3 syndrome and high-T3 syndrome: Consequences of step-up hypodeiodination, e.g. in critical illness as an example for type 1 allostasis, [20] or hyperdeiodination, as in type 2 allostasis, including posttraumatic stress disorder. [12] Resistance to thyroid hormone: Feedback loop interrupted on the level of pituitary thyroid hormone receptors.
The abnormality in the channel is thought to lead to shifts of potassium into cells, under conditions of high thyroxine (thyroid hormone) levels, usually with an additional precipitant. Treatment of the low levels of potassium in the blood, followed by correction of the hyperthyroidism, leads to complete resolution of the attacks.