Free Thyroxine (FT4)
What It Is
FT4 measures the unbound, active form of thyroxine, the main hormone produced by the thyroid gland.
Why It Matters
FT4 helps assess thyroid function and is essential for diagnosing hypothyroidism and hyperthyroidism.
If Levels Are High
Elevated FT4 may indicate an overactive thyroid (hyperthyroidism).
If Levels Are Low
Low FT4 suggests an underactive thyroid (hypothyroidism).
Preparation
No special preparation required. Take the sample before thyroid medication if applicable.
How Often to Test
Annually, or more frequently if on thyroid medication.
Important Disclaimer
This information is for educational purposes only and does not constitute medical advice or diagnosis. Results should be interpreted in clinical context by a qualified healthcare professional. If you have severe symptoms or urgent concerns, seek urgent medical help.