What is the Origin of Triiodothyronine (t3)?

The hormone's name is derived directly from its chemical composition: tri- (three) iodo- (iodine) thyronine (the basic amino acid backbone). Its discovery established the physiological hierarchy of thyroid hormones, confirming T3 as the primary effector molecule of the thyroid axis, despite T4 being secreted in greater quantity.

What is the Mechanism of Triiodothyronine (t3)?

T3 circulates in the blood, primarily bound to transport proteins like TBG, but the free fraction readily enters target cells. Inside the cell, T3 binds to specific nuclear thyroid hormone receptors (TRs), which then form heterodimers with the Retinoid X Receptor (RXR). This complex binds to specific DNA sequences, known as Thyroid Response Elements (TREs), in the promoter regions of target genes, directly modulating their transcription to regulate cellular metabolism and protein synthesis.

Triiodothyronine (t3)

Meaning

Triiodothyronine (T3) is the most potent and metabolically active of the thyroid hormones, characterized by the presence of three iodine atoms on its molecular structure. It is the critical hormone responsible for modulating the body’s basal metabolic rate, influencing oxygen consumption, heat production, and affecting the function of nearly all major organ systems. While some T3 is secreted directly by the thyroid gland, the majority of active T3 is produced through the peripheral deiodination of its precursor, thyroxine (T4).

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How Do Dietary Patterns Alter Thyroid Hormone Conversion?

Dietary patterns provide the essential micronutrients and energy signals that directly govern the body's conversion of inactive thyroid hormone to its active form.

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