This isolation Free T3 test measures the active form of the hormone T3, which is critical for regulating metabolism, energy production, and overall thyroid function. Assessing Free T3 is important because it reflects the hormone actually available to the body’s cells, providing a precise view of thyroid activity. This test is useful when other thyroid markers such as total T3, total T4, free T4, and TSH are within expected ranges, but further evaluation of active hormone levels is needed.

Fasting is not required for this test.

A provider will approve your labs, and your Lab Requisition Form will be emailed to you within 24 business hours. Labcorp will also have this on file. Please bring a valid photo ID to your nearest Labcorp location. Results will be securely emailed as soon as they are available.