Free T4 index
This test helps doctors evaluate your thyroid function.
Free T4 index Overview
Indirect measure of free T4. Corrects for high/low values of thyroxine-binding globulin (TBG).
The normal ranges for free T4 index are the following:
- Males: 1.5 - 3.0
- Females: 1.3 - 3.0
What the results mean
In healthy individuals, the free thyroxine index (FTI) remains relatively constant.
Higher than normal free T4 index indicates hyperthyroidism.
A lower than normal free T4 index indicates hypothyroidism.