BiomarkersTotal T3
Thyroid
Total T3
All T3 hormone, bound and free
On your report it may say: Total triiodothyronine, T3
Total T3 measures bound and free T3 together. Like total T4, it's affected by binding proteins.
Typical ranges · ng/dL
nmol/L = ng/dL × 0.0154
Some labs report in ng/mL; check your report's unit.
Ranges vary by lab, age and sex. The range printed on your report applies.
If it's low
May reflect an underactive thyroid or illness.
Common causes
- Underactive thyroid
- Illness or fasting
What you might notice
- Tiredness
If it's high
May reflect an overactive thyroid.
Common causes
- Overactive thyroid
- Pregnancy or oral contraceptives
What you might notice
- Fast heartbeat
Testing
- Who should test
- Part of some thyroid panels.
- How to prepare
- Stop biotin 2–3 days before.
- When to retest
- As your doctor advises.
What can help
SYNC doesn't recommend supplements from thyroid results. Thyroid problems need a doctor's diagnosis and treatment.
Discuss abnormal results with your doctor.
Common questions
Why are there both total and free tests?
Free tests avoid the effect of binding proteins.
Is it routine?
It appears in many Indian 'T3 T4 TSH' panels.
Explore further
Sources
Free nutrition assessment
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Build My Nutrition PlanFor general education only, not medical advice. Ranges shown are typical for adults; the range printed on your lab report applies. Talk to a qualified doctor about your results.