Liothyronine: Difference between revisions

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{{intro}}
{{Short description|Synthetic form of the thyroid hormone triiodothyronine}}
Thyroid hormones used therapeutically include crude thyroid extracts as well as synthetic forms of L-thyroxine (levothyroxine, T4) and L-triiodothyronine (liothyronine, T3). Thyroid hormone plays an essential role in growth and development and regulates multiple metabolic processes that are responsible for functional homeostasis.
{{Drugbox
| verifiedfields = changed
| verifiedrevid = 477002313
| IUPAC_name = (2S)-2-amino-3-[4-(4-hydroxy-3-iodophenoxy)-3,5-diiodophenyl]propanoic acid
| image = Triiodothyronine_200.svg
| image2 = Liotironina_sódica3D.png
}}


{{livtox}}
'''Liothyronine''' is a synthetic form of the [[thyroid hormone]] [[triiodothyronine]] (T3). It is used in the treatment of [[hypothyroidism]] and [[myxedema coma]]. Liothyronine is known for its rapid onset of action and is often used when a quick response is desired.
When given in high doses, thyroid hormone preparations can cause mild serum enzyme elevations. In addition, standard doses of levothyroxine have been linked to rare instances of mild, immunoallergic liver injury.


{{moa}}
==Medical uses==
Levothyroxine (lee" voe thye rox' een) is an orally available form of T4 that is commonly used to treat hypothyroidism and maintain the euthyroid state.  Other forms of thyroid hormone include thyroid extract and triiodothyronine (T3) or liothyronine (lye" oh thye' roe neen). Thyroid hormone is essential for normal growth, particularly of the central nervous system.  In adults, thyroid hormone maintains normal metabolism in virtually all organ systems.  Thyroxine (T4) is released from the thyroid gland, but is converted in the liver and other tissues to the active form, which is triiodothyronine (T3) which engages thyroid hormone receptors in the nucleus of cells, which together bind to DNA, leading to transcription of thyroid responsive genes that have multiple actions in different cells affecting cell metabolism. Thyroid hormone is necessary for normal growth and development, and deficiency of thyroid hormone results in cretinism in children and hypothyroidism and myxedema in adults with a multitude of symptoms, signs and laboratory abnormalities, including fatigue, weight gain, drowsiness, mental torpor and confusion.  Hypothyroidism is readily treated with oral forms of thyroid hormone which have been in clinical use for over 50 years, the most commonly used being desiccated thyroid (Armour Thyroid, 1950s), synthetic L-thyroxine or levothyroxine (T4, Synthroid, Levoxyl and others: 2002), and L-triiodothyronine or liothyronine (T3, Cytomel: 1956). Levothyroxine is currently one of the most commonly prescribed medications in the United States, with more than 100 million prescriptions filled yearly. 
Liothyronine is primarily used to treat [[hypothyroidism]], a condition where the thyroid gland does not produce enough thyroid hormones. It is also used in the treatment of [[myxedema coma]], a severe form of hypothyroidism that can be life-threatening. Additionally, liothyronine is sometimes used in [[thyroid function test]]s to suppress [[thyroid-stimulating hormone]] (TSH) production.


{{use}}
===Hypothyroidism===
The current indications are for maintenance of the euthyroid state. Levothyroxine is available in tablets at of 25 to 300 mcg for oral administration and as a lyophilized powder for parenteral use.
In patients with hypothyroidism, liothyronine helps to restore normal levels of T3, thereby alleviating symptoms such as fatigue, weight gain, and depression. It is often used in combination with [[levothyroxine]], another thyroid hormone, to provide a more balanced thyroid hormone replacement therapy.


{{dose}}
===Myxedema coma===
Levothyroxine is typically started at a low daily dose (25 to 50 mcg) and increased based upon clinical effect and serum levels of thyroid stimulating hormone (TSH) and free T4. The usual adult replacement dose is 75 to 125 mcg daily.
Myxedema coma is a medical emergency characterized by severe hypothyroidism, hypothermia, and altered mental status. Liothyronine is administered intravenously in this condition to rapidly increase T3 levels and improve the patient's metabolic state.


{{se}}
==Pharmacology==
Side effects are uncommon at correct replacement doses, but high doses can cause symptoms of hyperthyroidism such as fatigue, weight loss, headache, anxiety, tremor, muscle weakness, tachycardia, cardiac arrhythmias, menstrual abnormalities, irritability, emotional labiality, sleep disturbance and changes in personality.
Liothyronine is a synthetic form of T3, which is one of the two main hormones produced by the thyroid gland, the other being [[thyroxine]] (T4). T3 is the more active form of thyroid hormone and is responsible for regulating metabolism, heart rate, and body temperature.
{{coststubd}}
 
===Mechanism of action===
Liothyronine works by mimicking the effects of natural T3. It binds to thyroid hormone receptors in the body, influencing the expression of genes involved in metabolism and energy production. This leads to an increase in basal metabolic rate and affects protein synthesis and the sensitivity of the body to catecholamines.
 
===Pharmacokinetics===
Liothyronine is rapidly absorbed from the gastrointestinal tract, with peak serum levels occurring within 2 to 4 hours after oral administration. It has a half-life of approximately 2.5 days, which is shorter than that of levothyroxine. This shorter half-life allows for more precise control of hormone levels in the body.
 
==Side effects==
Common side effects of liothyronine include symptoms of hyperthyroidism, such as increased heart rate, anxiety, and weight loss. Overdose can lead to serious complications like [[atrial fibrillation]] and [[osteoporosis]].
 
==Contraindications==
Liothyronine is contraindicated in patients with uncorrected adrenal insufficiency and untreated thyrotoxicosis. Caution is advised in patients with cardiovascular disease due to the risk of exacerbating heart conditions.
 
==Related pages==
* [[Thyroid hormone]]
* [[Hypothyroidism]]
* [[Levothyroxine]]
* [[Thyroid function test]]
 
[[Category:Thyroid hormones]]
[[Category:Endocrinology]]
[[Category:Hormones]]

Latest revision as of 11:01, 23 March 2025

Synthetic form of the thyroid hormone triiodothyronine


Liothyronine
File:Triiodothyronine 200.svg
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Liothyronine is a synthetic form of the thyroid hormone triiodothyronine (T3). It is used in the treatment of hypothyroidism and myxedema coma. Liothyronine is known for its rapid onset of action and is often used when a quick response is desired.

Medical uses[edit]

Liothyronine is primarily used to treat hypothyroidism, a condition where the thyroid gland does not produce enough thyroid hormones. It is also used in the treatment of myxedema coma, a severe form of hypothyroidism that can be life-threatening. Additionally, liothyronine is sometimes used in thyroid function tests to suppress thyroid-stimulating hormone (TSH) production.

Hypothyroidism[edit]

In patients with hypothyroidism, liothyronine helps to restore normal levels of T3, thereby alleviating symptoms such as fatigue, weight gain, and depression. It is often used in combination with levothyroxine, another thyroid hormone, to provide a more balanced thyroid hormone replacement therapy.

Myxedema coma[edit]

Myxedema coma is a medical emergency characterized by severe hypothyroidism, hypothermia, and altered mental status. Liothyronine is administered intravenously in this condition to rapidly increase T3 levels and improve the patient's metabolic state.

Pharmacology[edit]

Liothyronine is a synthetic form of T3, which is one of the two main hormones produced by the thyroid gland, the other being thyroxine (T4). T3 is the more active form of thyroid hormone and is responsible for regulating metabolism, heart rate, and body temperature.

Mechanism of action[edit]

Liothyronine works by mimicking the effects of natural T3. It binds to thyroid hormone receptors in the body, influencing the expression of genes involved in metabolism and energy production. This leads to an increase in basal metabolic rate and affects protein synthesis and the sensitivity of the body to catecholamines.

Pharmacokinetics[edit]

Liothyronine is rapidly absorbed from the gastrointestinal tract, with peak serum levels occurring within 2 to 4 hours after oral administration. It has a half-life of approximately 2.5 days, which is shorter than that of levothyroxine. This shorter half-life allows for more precise control of hormone levels in the body.

Side effects[edit]

Common side effects of liothyronine include symptoms of hyperthyroidism, such as increased heart rate, anxiety, and weight loss. Overdose can lead to serious complications like atrial fibrillation and osteoporosis.

Contraindications[edit]

Liothyronine is contraindicated in patients with uncorrected adrenal insufficiency and untreated thyrotoxicosis. Caution is advised in patients with cardiovascular disease due to the risk of exacerbating heart conditions.

Related pages[edit]

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