thyroid function tests
Last reviewed 06/2021
The laboratory assessment of hypo- and hyperthyroidism has been simplified by the development of sensitive assays for:
- free T3 and free T4
Some laboratories still measure total T3 and total T4 and in such cases some estimate of the concentration of thyroid binding protein concentrations must be made.
Some typical reference ranges in adults are:
- TSH - 0.4 – 4.5 mU/L
- FT4 - 9.0 – 25 pmol/L
- FT3 - 3.5 – 7.8 nmol/L
- TT4 - 60 – 160 nmol/L
- TT3 - 1.2 – 2.6 nmol/L (1)
Note that reference ranges may vary between laboratories.