FREE_T4
Thyroid

Free Thyroxine

also known as Free T4

NORMAL_RANGE
0.8 – 1.8 ng/dL
UNIT
ng/dL

/WHAT_IT_IS

Free T4 is the storage form of thyroid hormone — most of it gets converted to T3 in tissues.

/NORMAL_RANGE

Reference: 0.8–1.8 ng/dL.

What does high Free T4 mean?

  • +Hyperthyroidism, T4 supplementation.

What does low Free T4 mean?

  • +Hypothyroidism, severe illness.

/ON_TRT

Pair with TSH and free T3 for a complete thyroid picture.

/RELATED

/TRACK_THIS

Track Free T4 in the app.

Upload your lab PDF — MyTRT extracts every marker with Gemini Vision. Charts, trends, and TRT-aware insights. Free on iOS and Android.

Last reviewed: 2026-06-04 · MyTRT does not provide medical advice. Always consult your physician.