Free T4

MeasuredUseful

The main thyroid hormone available to your tissues.

The standard follow-up once TSH comes back abnormal.

How we rate it — Useful

Worth doing for a specific reason — a risk factor, a symptom, an age group.

This rating and the description above were written against published screening guidelines by someone who is not a clinician, and are awaiting review by one. We would rather say that than imply an authority we do not have.

Check-ups that include it

In 12 of the 78check-ups we track — 15%. Cheapest first.

Also sold as

Every one of these names refers to this same test. Resolving them to one canonical entry is what makes an honest comparison possible.

free t4 · free thyroxine · ft4

Information here is for comparing packages, not for diagnosing yourself. Talk to a doctor about which tests you actually need.