Total T3
Understand Total T3 levels for thyroid hormone function and metabolic rate assessment. Monitor thyroid health with precision tracking.
What is Total T3?
Total T3 (triiodothyronine) measures all T3 hormone in the blood, including both bound and free forms. About 99.7% is bound to proteins, while only a small fraction remains free and active. Total T3 provides an overall assessment of T3 production and availability, though free T3 better reflects actual hormone activity.
Why is it Tested?
Doctors order Total T3 to evaluate thyroid function, particularly when hyperthyroidism is suspected or when monitoring thyroid treatment. It’s useful for detecting T3 thyrotoxicosis and assessing overall thyroid hormone production when used alongside other thyroid markers.
Normal Ranges
Reference ranges vary by lab but typically fall within:
- Adults: 80–200 ng/dL
Total T3 levels may decline slightly with age and can be affected by protein binding changes.
Reference ranges vary by authority. Track yours across multiple standards with automatic unit conversions in LabsVault.
What do Abnormal Results Mean?
Abnormal results are not a diagnosis. Always discuss your results with a qualified healthcare provider before making any medical decisions.
Low Total T3
Low levels may indicate:
- Hypothyroidism
- Non-thyroidal illness syndrome
- Malnutrition or chronic illness
- Medications affecting thyroid function
High Total T3
Elevated Total T3 may suggest:
- Hyperthyroidism (various causes)
- T3 thyrotoxicosis
- Excessive thyroid hormone replacement
- Early thyroiditis (temporary elevation)
How to Track Over Time
Total T3 patterns help assess thyroid function trends and treatment response. While less sensitive than Free T3 for detecting changes in hormone activity, Total T3 provides valuable context about overall thyroid hormone production and helps identify T3-predominant thyroid conditions.
Track your Total T3 results over time
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