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 17 of the 93 check-ups we track, 18%. Cheapest first.

and 5 more.

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
  • thyroxine free

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