T3 Free
- Thyroid
Learn what T3 Free measures and how it fits into your health data.
What is T3 Free?
Free Triiodothyronine (Free T3) measures the unbound, biologically active form of T3, the most potent thyroid hormone, primarily produced by conversion from T4 in peripheral tissues. Free T3 directly influences metabolic rate and cellular function. Low levels can cause hypothyroid symptoms even if TSH and Free T4 are normal.
Testing options
Frequently ordered with:
Panels with this test:
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