# Thyroxine (T4)

> This test measures the total amount of thyroxine (T4), a hormone produced by your thyroid gland that controls how your body uses energy. It helps show whether your thyroid is overactive or underactive, which is often checked when patients experience fatigue or unexplained weight changes. While this measurement helps screen for thyroid disorders, it cannot diagnose a specific condition on its own because protein levels, medications, and other illnesses can also affect T4 levels.

- Labcorp code: 001149
- 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=001149&ref=assistant

## 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.