Total T4
Track Total T4 levels for thyroid gland function and hormone production assessment. Learn about thyroid health monitoring insights.
What is Total T4?
Total T4 (thyroxine) measures both free and protein-bound T4 hormone in your blood. T4 is the primary hormone produced by the thyroid gland and is converted to the more active T3 hormone in tissues throughout your body.
Why is it Tested?
Doctors order total T4 to evaluate thyroid function, investigate hyperthyroidism or hypothyroidism, and monitor thyroid hormone replacement therapy. While free T4 is often preferred, total T4 provides additional information about thyroid hormone binding proteins.
Normal Ranges
Reference ranges for total T4:
- Normal: 5.0–12.0 μg/dL
Levels can be affected by pregnancy, birth control pills, and other medications that alter thyroid hormone binding proteins.
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 T4
Reduced levels may indicate:
- Hypothyroidism
- Pituitary dysfunction
- Severe illness
- Certain medications
- Protein deficiency
High Total T4
Elevated levels suggest:
- Hyperthyroidism
- Thyroiditis
- Excessive thyroid medication
- Pregnancy
- Estrogen therapy
How to Track Over Time
Total T4 levels help monitor thyroid function and medication effectiveness. Changes may lag behind clinical symptoms, and levels should be interpreted alongside TSH and free T4. Regular tracking helps optimize thyroid hormone replacement therapy dosing.
Track your Total T4 results over time
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