| Test | Conventional | SI | Threshold |
|---|---|---|---|
| Free Thyroxine (Free T4) | 0.8-1.8 ng/dL | 10-23 pmol/L | - |
| Free Triiodothyronine (Free T3) | 2.3-4.2 pg/mL | 3.5-6.5 pmol/L | - |
| Thyroid Peroxidase Antibody (TPO Ab) | < 35 (negative) IU/mL | < 35 kIU/L | - |
| Thyroid-Stimulating Hormone (TSH) | 0.4-4 mIU/L | 0.4-4 mIU/L | - |
| Total Thyroxine (Total T4) | 5-12 µg/dL | 64-154 nmol/L | - |
| Total Triiodothyronine (Total T3) | 80-200 ng/dL | 1.2-3.1 nmol/L | - |
Panel
Thyroid Function
TSH, free and total T4/T3, and thyroid antibodies. 6 tests.
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Frequently asked questions
What tests are in a Thyroid Function?
The Thyroid Function on this page lists 6 tests: Free Thyroxine (Free T4), Free Triiodothyronine (Free T3), Thyroid Peroxidase Antibody (TPO Ab), Thyroid-Stimulating Hormone (TSH), Total Thyroxine (Total T4), Total Triiodothyronine (Total T3). Each is shown with its conventional and SI teaching reference range.
What does the Thyroid Function check for?
TSH, free and total T4/T3, and thyroid antibodies. These are educational teaching values - ranges vary by laboratory and method, and are not for clinical decisions.