Thyroid
Total T3
LOINC 3053-6 · ng/dL
Ranges
Reference range: 80–200 ng/dL
What it is
Total T3 measures all of the triiodothyronine in your blood, both the active free portion and the part bound to proteins.
Why it matters
It supports the assessment of thyroid function, particularly an overactive thyroid.
What high values can mean
A higher value can indicate an overactive thyroid; it is also affected by proteins that bind thyroid hormone.
What low values can mean
A lower value can occur with an underactive thyroid or during illness.
How to improve it
Thyroid hormones are managed medically; consistent treatment keeps them in range.
Food & lifestyle
Adequate iodine and selenium support thyroid function; dosing is guided by your clinician.
Preparing for the test
A blood test; fasting is not required — follow your lab's instructions.
When to talk to a doctor
Discuss abnormal Total T3 with a doctor, interpreted with TSH and Free T4.
Related markers
Sources
- MedlinePlus (NIH)
- Testing.com (AACC)
Content reviewed on June 26, 2026
Medical disclaimer
This content is for educational purposes only. It is not medical advice and does not diagnose, treat, or prevent any condition. Reference ranges vary between laboratories — always use the range printed on your report and discuss your results with a healthcare professional.
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