T3 is not always converted from T4: De novo T3 synthesis

Choosing Wisely Canada, in its campaign to prevent "unnecessary" Free T3 testing in hypothyroidism, says this at the opening of their justification: "T4 is converted into T3 at the cellular level in virtually all organs." (1) Such a statement makes it seem like T3 hormone only originates from T4 hormone. Admittedly, debate and uncertainty has … Continue reading T3 is not always converted from T4: De novo T3 synthesis