Free T3 is the active, unbound form of triiodothyronine, one of the main thyroid hormones. The thyroid gland in your neck makes hormones that control how fast your body uses energy. The free T3 blood test measures the active form of this thyroid hormone. It helps doctors assess thyroid function, especially when an overactive thyroid is suspected.

Before the Test

Tell your doctor about all medicines and supplements, especially thyroid medicines and biotin (a common supplement), as these can affect results.

Mention any recent illness.

Fasting is usually not required.

During the Test

A trained Orange Health Labs professional will collect your sample during the visit.

Follow the instructions given to you at the time of collection.

The sample is labelled and sent to the laboratory for testing.

Let the collection team know if you feel unwell during the procedure.

It is recommended:

To investigate symptoms of an overactive thyroid, such as weight loss, fast heartbeat, or feeling hot and anxious.

To add detail to other thyroid tests such as TSH and T4.

To help diagnose and monitor thyroid disorders.

To track the response to thyroid treatment.

When thyroid problems are suspected. Often read together with TSH and T4.