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Interpret Your Free Triiodothyronine Results
Enter your Free T3 value below and get an instant, free AI interpretation — a plain-English explanation checked against WHO/IFCC reference ranges.
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This AI-generated interpretation is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Results may vary based on individual health factors not captured here.
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Free Triiodothyronine Normal Ranges
Free T3 is the most biologically active thyroid hormone — it exerts most of the metabolic effects at the cellular level.
| Age Group | Reference Range | Unit | Notes |
|---|---|---|---|
| Adults (18–64) | 2.3 – 4.2 | pg/mL | — |
Also reported in: pmol/L.
Common Causes of High Free T3
Graves' disease (often FT3 rises before FT4)T3 toxicosis (toxic adenoma secreting primarily T3)Excessive tri-iodothyronine (liothyronine) supplementation
Common Causes of Low Free T3
Hypothyroidism (FT3 falls late, after FT4)Non-thyroidal illness (sick euthyroid) — most common cause of low FT3Amiodarone (blocks T4 to T3 conversion)
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