How Free T4 appears on your report
Look for Free Thyroxine (FT4). It may also be printed as Free T4. The result is normally shown in pmol/L, next to the reference interval used by the laboratory that ran the test.
Note the collection date before you compare it with anything, along with the context that matters for this marker: thyroid medicines, illness, pregnancy, supplements and collection timing can affect it. Read it with TSH.
Free T4 range in Australia
Vector tracks Free T4 against an optimal range of 12.0–20.0 pmol/L. Australia has no nationally harmonised reference interval for this marker, so the interval printed on your report varies with the laboratory and the assay it used.
Vector’s optimal range is the band the app tracks against and the one printed in the doctor report. Why the two differ.
What to read alongside Free T4
A single marker rarely explains itself. These results are commonly interpreted together with Free T4, and Vector keeps them within reach of each other as your record grows.
Tracking Free T4 over time
One Free T4 result is a single point. Import the report into Vector, check the extracted value, unit and collection date, and it becomes the start of a series instead — with each later report adding a dated point you can actually compare against.
Further reading
Free T4 is read the same way every other result on the report is. These two guides cover that method rather than this marker:
- How to read an Australian pathology report — A practical guide to dates, units, reference intervals and the context that belongs beside an Australian pathology result.
- Pathology report reference ranges: what they mean — Understand the laboratory interval, Australian guidance and the product context Vector adds to a result over time.
Common questions
What is a normal Free T4 range in Australia?
Australia has no nationally harmonised reference interval for Free T4, so the range printed on your report varies with the laboratory and the assay it used — always read your result against the interval beside it. Vector tracks Free T4 against an optimal range of 12.0–20.0 pmol/L, which is deliberately tighter than a population reference interval.
What is the optimal Free T4 level?
Vector treats 12.0–20.0 pmol/L as the optimal range for Free T4. An optimal range is a target the app tracks against, not a clinical threshold, and it can differ from the interval your laboratory prints.
What unit is Free T4 reported in on Australian pathology reports?
Free T4 is usually reported in pmol/L on Australian pathology reports. The performing laboratory prints a reference interval in the same unit beside the result, and that interval is the one that governs your individual result.
What can change your Free T4 result?
Thyroid medicines, illness, pregnancy, supplements and collection timing can affect it. Read it with TSH.
What else is Free T4 called?
Free Thyroxine (FT4) may also appear as Free T4 on a pathology report. Laboratories differ in the label they print, which is why Vector matches on several names for the same analyte.
Sources
- RCPA Manual: Free T4Australian pathology reference for this test and related result context.
- Healthdirect: thyroid problemsGeneral context for thyroid function and symptoms.
Published 2 August 2026 · Updated 3 August 2026 · Author Vector