T3 Uptake
- Sample Type
- Standard
- Fasting
- No
- Unit
- %
T3 Uptake is an indirect measure of the available binding sites on Thyroxine-Binding Globulin (TBG). It is not a direct measurement of T3 hormone levels. Its primary clinical utility is to calculate the Free Thyroxine Index (FTI), which helps correct for variations in binding proteins that can occur due to pregnancy, medications, or liver disease. In modern practice, it is often replaced by direct Free T4 assays.
Check Your Result
Check Your Result
Enter your lab result to see where you stand compared to the standard reference range.
Why Context Matters
Abnormal results often reflect changes in the amount of binding proteins (TBG) rather than thyroid gland dysfunction. For example, high estrogen levels (pregnancy, oral contraceptives) increase TBG, which lowers T3 uptake, mimicking hypothyroidism on paper while the patient is actually euthyroid.
Lab ranges are statistical averages, not biological laws. "Normal" for a 20-year-old male isn't normal for a 60-year-old female.
Clinical References
Source-of-truth databases and clinical guidelines for T3 Uptake:
Official Sources
- T3RU test: MedlinePlus Medical EncyclopediaMedlinePlus
Research & Guidelines
- PubMed: T3 Uptake Clinical GuidelinesNCBI / PubMed
Related Indicators
Medically Reviewed by Dr. Binoy Babu, MBBS
Board Certified Doctor • 10+ Years Clinical Experience
Dr. Babu is a practicing physician dedicated to empowering patients with clear, actionable medical information. He founded 2opi to bridge the gap between complex lab reports and patient understanding, ensuring everyone has access to a reliable second opinion.
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