Free T4
Also known as Free Thyroxine
What it is
Free T4 measures the active, unbound form of thyroxine, the primary hormone your thyroid gland produces, most of which is later converted to the more active T3 in tissues throughout the body.
Why it matters
Free T4 is the direct output of the thyroid gland itself, which makes it a useful complement to TSH, which measures the pituitary's signal to the thyroid rather than the thyroid's actual output. Reading TSH and Free T4 together helps clarify where in the feedback loop, pituitary or thyroid, an abnormal result is originating, which matters because the appropriate next step differs depending on which end of that loop is involved. Combined with Free T3, it gives a fuller picture of thyroid hormone production and conversion.
Free T4 is one of the markers in Zaro's Signal panel and every tier above it.
This information is for educational purposes and is not a substitute for professional medical advice. Always talk to a physician about your specific results and health history.
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