Free T3
What it measures
Free T3 measures the active, unbound form of triiodothyronine, a thyroid hormone that's more potent but shorter-lived than T4.
Often reported in pg/mL. Reference ranges differ between laboratories, ages and sexes, so always compare with the range printed on your own report.
Why it matters
Free T3 is usually checked alongside TSH and free T4 rather than on its own, since thyroid function is best read as a set of related results.
Questions worth asking
- How does this fit with my TSH and free T4 results?
- Could recent illness or medication changes be relevant?
- Is further thyroid workup worth discussing?
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Educational information only. Not a diagnosis, not treatment advice, and not a substitute for a licensed healthcare professional.