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Thyroid

Free T3

Your laboratory may print this as FT3, Free triiodothyronine. Usually reported in pg/mL.

On your report

NameFree T3
Also printed asFT3 · Free triiodothyronine
Usual unitpg/mL
Reference rangePrinted by your own laboratory. We publish none of our own.

Comparing two results

A change under about 14.1% may be nothing at all

Free T3 varies within the same healthy person from day to day — for this value, by about 5.1%. So two results can differ without anything having changed. Below roughly 14.1%, a difference is as likely to be ordinary variation as anything else.

This figure is a lower bound, deliberately. The full calculation also includes the variation of the specific machine that ran your sample, which belongs to your laboratory and differs between them. Leaving it out makes the threshold smaller, so this flags changes that may turn out to be nothing — rather than missing ones that matter.

Biological variation figure from the EFLM BVD meta-analysis. Calculated as 2.77 × CVI.

What MedicaCare AI does with this value

Photograph the report and you get your own free t3 explained against the range your laboratory printed — plus every other value on the page, and somewhere to ask what you actually want to know.

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Usually printed alongside it

TSHFree T4