All lab markers

Thyroid

Free T3

The active thyroid hormone your cells actually use. Conversion needs iron, selenium and low stress load. Lower results are the ones to watch.

In more detail

Active hormone. Conversion needs iron, selenium and low cortisol load.

What commonly moves it

  • Free T4
  • Ferritin
  • Systemic inflammationRaises hepcidin (blocking iron), ESR/fibrinogen, and blunts T3 conversion.
  • HPA-axis strainChronic stress load flattens cortisol rhythm and depletes DHEA-S.

What it can affect downstream

VO2 Max

These are commonly described physiological relationships, shared for education. They are not a diagnosis and cannot account for your medications, history, or symptoms — discuss your results with a licensed clinician.

Watching Free T3 over time?

Dose Compass charts each draw, flags meaningful moves, and helps you prepare questions for your clinician.

Start tracking