---
title: "Free T4 (FT4) Test: What It Measures & What Results Mean"
description: "A Free T4 (FT4) test measures the active thyroid hormone in your blood to help assess thyroid function, with convenient ordering through Vitals Vault labs."
canonical: "https://www.vitalsvault.com/biomarkers/t4-free-ft4"
last-updated: 2026-08-22
---

# Free T4 (FT4) Test: What It Measures & What Results Mean

> A Free T4 (FT4) test measures the active thyroid hormone in your blood to help assess thyroid function, with convenient ordering through Vitals Vault labs.

---

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