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Thyroid Conversion T4 T3

Meaning

The crucial, highly regulated physiological process of deiodination, wherein the relatively inactive prohormone thyroxine (T4), which is secreted primarily by the thyroid gland, is converted into the biologically potent and active hormone triiodothyronine (T3) by specific deiodinase enzymes in peripheral tissues. This conversion is the absolute rate-limiting step for thyroid hormone action at the cellular level, directly influencing the basal metabolic rate, systemic body temperature, and cellular energy production. Clinical assessment of this peripheral conversion is vital for accurately diagnosing and effectively managing states of subclinical hypothyroidism.