Comparative Analysis of Elevated Serum Total and Free Triiodothyronine Results Obtained by Immunoassays
Authors' conclusion
The TT3 and FT3 results were generally well correlated, with elevated FT3 demonstrating performance superior to that of elevated TT3.
Study context
- Population
- Blood samples with thyroid-stimulating hormone (TSH), free T4 (FT4), total T3 (TT3) and free T3 (FT3) measured in parallel on a fully automated electrochemiluminescence immunoassay platform605 blood samples
- Participants
- 465 participants
- Exposure
- Total T3 vs FT3 measured in parallel
- Outcome
- Correlation between TT3 and FT3 and discordance of elevated values
Methodological detailssingle electrochemiluminescence immunoassay platform, manufacturer reference intervals
- Single electrochemiluminescence immunoassay platform
- Manufacturer reference intervals
Main finding
As reported in the abstract
Correlation TT3 vs FT3, TT3 ≤200 ng/dL: b (95% CI 0.0019-0.0021)
b = 0.0020, r = 0.841
Correlation TT3 vs FT3, TT3 >200 ng/dL: b (95% CI 0.0044-0.0064)
b = 0.0054, r = 0.855
Patients with elevated T3 values
41
Elevation of either TT3 or FT3 only (mild discordance), of 41 patients
13
Observational data: associations, not effects.
Original publication
Comparative Analysis of Elevated Serum Total and Free Triiodothyronine Results Obtained by Immunoassays. Thyroid. Published 9 May 2026. doi:10.
Composed by AI from the published abstract and checked against it. How Briefs are made →