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Change in Thyroid Hormone Metabolite Concentrations Across Different Thyroid States
Rutchanna M S Jongejan1,2, Evert F S van Velsen2,3, Marcel E Meima2,3
1Department of Clinical Chemistry, Rotterdam, The Netherlands.
Thyroid : Official Journal of the American Thyroid Association
|November 22, 2021
Summary
Thyroid hormone metabolites decrease after thyroidectomy and increase with levothyroxine (LT4) therapy, indicating dependence on peripheral T4 metabolism. T3 levels remained normal during LT4 therapy, suggesting some thyroidal origin.
Area of Science:
- Endocrinology
- Metabolomics
- Thyroid Disease Research
Background:
- Limited understanding of thyroid hormone metabolite (THM) concentrations in altered thyroid states.
- Uncertainty regarding the impact of thyroidectomy and levothyroxine (LT4) replacement on THM levels.
- Differentiated thyroid cancer (DTC) treatment offers a unique model to study THM across various thyroid states.
Purpose of the Study:
- To prospectively investigate nine thyroid hormones and metabolites (THMs) in patients with DTC.
- To determine how thyroidectomy and LT4 therapy affect THM concentrations.
- To explore associations between THM levels and age, sex, and kidney function.
Main Methods:
- Prospective study of 77 DTC patients (aged 18-80) at Erasmus MC.
- Blood samples collected in euthyroid, hypothyroid (post-surgery), and [sub]hyperthyroid (LT4 therapy) states.
- Quantification of nine THMs using liquid chromatography/tandem mass spectrometry; statistical analysis for state comparisons and determinant associations.
Main Results:
- All measured THMs decreased significantly in the hypothyroid state and increased in the [sub]hyperthyroid state compared to the euthyroid state.
- T3 concentrations remained within the reference interval during LT4 therapy.
- Higher age correlated with increased 3-monoiodothyronine (3-T1), women had higher L-thyronine, and better kidney function correlated with lower 3-T1.
Conclusions:
- THM levels are significantly altered by thyroidectomy and LT4 therapy.
- Peripheral extrathyroidal metabolism of thyroxine (T4) is crucial for THM formation.
- The thyroid gland may contribute to circulating T3 levels, even during LT4 therapy.
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