FREE_T3
Thyroid

Free Triiodothyronine

also known as Free T3

NORMAL_RANGE
2.3 – 4.2 pg/mL
UNIT
pg/mL

/WHAT_IT_IS

Free T3 is the biologically active thyroid hormone. TSH alone can miss thyroid dysfunction — measuring free T3 catches more cases.

/NORMAL_RANGE

Reference: 2.3–4.2 pg/mL. Optimal: upper half of range.

What does high Free T3 mean?

  • +Hyperthyroidism, T3 supplementation.

What does low Free T3 mean?

  • +Hypothyroidism, T3 conversion issues, chronic dieting.

/ON_TRT

If TSH is normal but you have hypothyroid symptoms on TRT, check free T3. Some men have impaired T4→T3 conversion and need T3-containing thyroid replacement.

/RELATED

/TRACK_THIS

Track Free T3 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.