Reviewed: 16. April 2026
fT3 Free Triiodothyronine (FT3)
Unit: pg/ml
Quick Explanation
fT3 (free triiodothyronine) is the active thyroid hormone that influences metabolism, heart rate, and many body functions. Elevated levels may indicate hyperthyroidism, while low levels may point to hypothyroidism. Discuss any deviations with your doctor.
📊 Reference Values
ℹ️ Reference ranges may vary slightly between laboratories. Always compare your value with the reference range from your own lab report.
🔍 Possible Causes
Value too high — possible causes
- ·Hyperthyroidism
- ·Graves' disease
- ·Thyroid inflammation
Value too low — possible causes
- ·Hypothyroidism
- ·Hashimoto's thyroiditis
- ·Iodine deficiency
- ·Severe systemic illness
This list shows possible causes — not a diagnosis. Only your doctor can correctly interpret your result.
🩺 Questions for Your Doctor
- →How should my fT3 be interpreted in relation to fT4 and TSH?
- →Is there a thyroid disorder?
- →Do I need a thyroid scan?
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Medical Disclaimer
The content on this page is for general information only and does not replace professional medical advice, diagnosis, or treatment. Always consult your doctor or pharmacist for health-related questions. Lab values should always be assessed in the context of your personal medical history.