What is Free Thyroxine (Free T4)?
Free Thyroxine is measured as part of a thyroid panel. Your Free T4 is in a healthy range.
What does a high Free Thyroxine mean?
Your Free T4 is high, which can indicate an overactive thyroid. Your doctor will look at this alongside TSH and your symptoms.
What does a low Free Thyroxine mean?
Your Free T4 is low, which suggests the thyroid may be underactive (hypothyroidism). This is usually interpreted together with your TSH.
Understand your whole report, not just one number
A single value rarely tells the full story — Free Thyroxine is best read alongside the rest of your panel. Paste your values or upload your report and get a plain-English explanation of every marker, with the important results flagged.