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Published on: March 17, 2023
Thr92Ala polymorphism in the type 2 deiodinase is not associated with T4 dose in athyroid patients or patients with
K A Heemstra1, H C Hoftijzer, W M van der Deure
1Department of Endocrinology and Metabolism, Leiden University Medical Center, Leiden, the Netherlands.
Objective:
The type 2 deiodinase (D2)-Thr92Ala polymorphism has been associated with decreased D2 activity in some in vitro experiments but not in others. So far no association between the D2-Thr92Ala polymorphism and serum thyroid hormone levels has been observed in humans, but in a recent study in athyroid patients, it was suggested that patients homozygous for the Ala(92) allele needed higher T4 doses to achieve TSH suppression. We studied the association between the D2-Thr92Ala polymorphism with thyroid hormone levels and T4 dosage, in patients treated for differentiated thyroid carcinoma (DTC) and in a group of patients treated for Hashimoto thyroiditis.
Design:
Cross-sectional study.
Patients:
We studied 154 patients with DTC treated with TSH suppressive thyroid hormone replacement therapy for longer than 3 years and 141 patients with Hashimoto thyroiditis treated for at least 6 months with T4.
Measurements:
In all patients, serum levels of TSH, free T4, T3 and reverse T3 were measured and genotypes of the D2-Thr92Ala polymorphism were determined by Taqman assay. Univariate regression analysis was performed to determine the relation between T4 dosages and the D2-Thr92Ala polymorphism corrected for age, gender, BMI and serum TSH levels.
Results:
Both in DTC patients and Hashimoto patients, no association was observed between serum thyroid hormone levels or T4 dosages in presence of the D2-Thr92Ala polymorphism. Categorization of DTC patients according to degree of TSH suppression did not change these results.
Conclusion:
The D2-Thr92Ala polymorphism is not associated with thyroid hormone levels or T4 dose in patients treated for DTC or Hashimoto thyroiditis.
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