Diagnostic Utility of Genetic Testing in Hyperthyroxinemia With Non‐Suppressed Thyroid-stimulating Hormone (TSH)
Authors' conclusion
Our findings highlight the critical role of molecular testing in accurately diagnosing the underlying cause of elevated FT4 with non-suppressed TSH and in preventing unnecessary interventions. Hotspot analysis of the ALB gene is recommended as a first-line test, particularly in asymptomatic individuals.
Study context
- Population
- Children with elevated free thyroxine (FT4) and non-suppressed TSH, 19 unrelated families19 unrelated families
- Participants
- 25 children
- Exposure
- RTHβ vs familial dysalbuminemic hyperthyroxinemia (FDH)
- RTHβn = 6
- FDHn = 12
- Outcome
- Diagnostic yield of genetic testing
Main finding
As reported in the abstract
- THRB sequencing performed
- 21 children from 18 families
- ALB sequencing completed
- 16 children from 13 families
- Novel THRB variant identified
- c.997 G > C, p.(Glu333Gln)
Observational data: associations, not effects.
Further findings
| Outcome | RTHβ | FDH |
|---|---|---|
| Tachycardia | 50% | 0 events |
Tachycardia
- No FDH-confirmed patient had tachycardia or other signs of thyroid dysfunction
Thyroid function tests, RTHβ vs FDH
- FT4 and TSH similar between RTHβ and FDH
- FT3 tended to be lower in FDH
- FT3/FT4 ratio did not differ significantly
Original publication
Diagnostic Utility of Genetic Testing in Hyperthyroxinemia With Non‐Suppressed TSH. Clin Endocrinol (Oxf). Published 9 March 2026. doi:10.
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