Total T4

Specialist

also thyroxine

What it isThe combined measurement of T4 that is bound to transport proteins plus the small free fraction.

DoesReports the full T4 pool, but doesn't distinguish active from inactive bound hormone.

GoodA mid-range total T4 with normal free T4 suggests balanced thyroid output and transport protein levels.

BadDistortions from estrogen, pregnancy, or liver disease that shift transport proteins make total T4 misleading — Free T4 is the more reliable measure.

Standard

4.5–12 µg/dL.

Optimal

7–9 µg/dL (narrow target)

Modifiers

Rises with estrogen, pregnancy; falls with liver and kidney disease.

How to optimize

Lifestyle: Same as Free T4.
Diet: Same as Free T4.
Supplements: Same as Free T4.
Peptides: —
Drugs: Levothyroxine.

within Thyroid