What is the Origin of T3 T4 Levels?

This notation comes directly from clinical endocrinology, representing the two primary iodine-containing hormones produced by the thyroid gland. T4 is the primary secretion, which is largely converted peripherally into the more potent T3.

What is the Mechanism of T3 T4 Levels?

T4 is converted to T3 via deiodinase enzymes in peripheral tissues, with T3 then binding to nuclear thyroid hormone receptors (TRs). This binding complex modulates gene transcription, increasing the expression of genes involved in mitochondrial respiration and substrate oxidation, thereby dictating the speed of cellular metabolism.

T3 T4 Levels ∞ Area

T3 T4 Levels

Meaning

The circulating concentrations of the active thyroid hormones Triiodothyronine (T3) and Thyroxine (T4) measured in the peripheral circulation, which are essential regulators of basal metabolic rate, thermogenesis, and cellular energy expenditure. Accurate assessment of these levels, often alongside TSH, defines thyroid axis functionality. These are direct proxies for metabolic control.