# Triiodothyronine (T3), Free

> This test measures the amount of free triiodothyronine (T3) in your blood, which is the active form of a thyroid hormone that is not attached to proteins. It helps show how well your thyroid is regulating your body's energy and metabolism, particularly if you have symptoms like rapid heartbeat or unexplained weight loss. Doctors use this measurement to help identify or rule out an overactive thyroid gland, also known as hyperthyroidism. However, this test alone cannot determine the specific underlying cause of a thyroid condition without further evaluation.

- Labcorp code: 010389
- Category: [Thyroid](https://app.picardo.health/labs/tests/thyroid.md)
- Price: shown at checkout, before payment.
- Blood draw: free at a Labcorp location, or $75.00 at home.
- Order link: https://app.picardo.health/labs/order?tests=010389&ref=assistant
- Already in these panels: [Postpartum Panel](https://app.picardo.health/labs/panels/postpartum.md), [Thyroid & Autoimmunity](https://app.picardo.health/labs/panels/thyroid-autoimmunity.md)

## About ordering

A licensed physician reviews every order before any test is run, and results arrive in the person's Picardo account. Ordering is open to adults 18 and over in the US, except New York, New Jersey, Rhode Island, Pennsylvania, Maryland, Massachusetts, Hawaii and Maine. General health information, not medical advice.