# Thyroxine (T4), Free, Direct

> This test measures the amount of free thyroxine (T4) in your blood, which is the active form of thyroid hormone available for your body to use. It helps show how well your thyroid gland is regulating your metabolism and energy levels. Doctors use this measurement to help identify an overactive or underactive thyroid, even when other blood proteins might interfere with standard tests. However, this test alone cannot determine the specific cause of a thyroid disorder without additional testing.

- Labcorp code: 001974
- 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=001974&ref=assistant
- Already in these panels: [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.