About this test
T3 is one of the two main hormones made by the thyroid gland. It affects energy use, heart rate and body temperature. T3 is often checked together with TSH and T4 to understand thyroid function.
Why it is done
- To help diagnose an overactive thyroid.
- To look further into an abnormal TSH result.
- To monitor thyroid conditions, as advised by the doctor.
Preparation
Fasting is not usually required. Tell us about thyroid medicines or supplements such as biotin.
This information is general and is not medical advice. Please speak to your doctor about your results and treatment.