Thyroid Function
Normal range 2.3-4.2 pg/mL (3.5-6.5 pmol/L SI). Specimen: Serum.
Also known as: FT3.
Combined adult band. LabVals does not publish separate men's, women's, or pediatric ranges for Free Triiodothyronine (Free T3); those can be narrower than the band shown.
| Specimen | Serum |
|---|---|
| Conventional range | 2.3-4.2 pg/mL |
| SI range | 3.5-6.5 pmol/L |
| Conversion factor | ×1.536 (conventional → SI) |
| Panel | Thyroid Function |
Convert any Free Triiodothyronine (Free T3) result between units on the unit converter.
The standard teaching reference range for Free Triiodothyronine (Free T3) is 2.3-4.2 pg/mL in conventional units, or 3.5-6.5 pmol/L in SI units. This value is measured in serum.
Source: Adult reference values compiled from Pagana & Pagana, Mosby's Diagnostic and Laboratory Test Reference, and Fischbach & Dunning, A Manual of Laboratory and Diagnostic Tests. Reference ranges vary by laboratory, method, age, sex, and population - always use the range printed on the actual result.
Above the range
What causes a high Free Triiodothyronine (Free T3)? Read as its own page
Below the range
What causes a low Free Triiodothyronine (Free T3)? Read as its own page
At the bedside
You have the Free Triiodothyronine (Free T3) range. Premium unlocks the 6-card Thyroid Function flashcard deck with mastery tracking, study sheets that put several panels on one printable page, and unlimited practice across all 440 quiz questions - the free round stops at 10 a day.
Same panel