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Cellular T3 Availability

Meaning

Cellular T3 availability is the measure of the biologically active thyroid hormone, triiodothyronine (T3), that is successfully transported into a target cell and is accessible to bind with its nuclear receptor to initiate genetic transcription. This metric provides a more accurate reflection of a patient’s true thyroid status at the tissue level compared to serum T3 alone, as it accounts for local conversion and transport mechanisms. Optimal availability is non-negotiable for regulating cellular metabolism and energy production across the body.