Association between TSH suppression therapy and type 2 deiodinase gene polymorphism in differentiated thyroid carcinoma.

Introduction: Oral levothyroxine (L-T4) suppression of thyroid-stimulating hormone (TSH) levels is the most commonly used clinical approach to manage and treat patients after thyroid cancer surgery. This study aimed to investigate the association between TSH suppression therapy and type 2 deiodinase gene (DIO2) polymorphism in differentiated thyroid carcinoma (DTC).

Material And Methods: A total of 240 patients with DTC who received total thyroidectomy (TT; 120) and hemithyroidectomy (HT; 120) were enrolled in this study. The serum TSH, free triiodothyronine (FT3), and free thyroxine (FT4) levels were detected using an automatic serum immune analyser and electrochemiluminescence immunoassay. Based on the results of DIO2 gene detection, 3 genotypes of Thr92Ala were detected.

Results: The serum TSH levels were inhibited after oral L-T4 treatment, but the proportion of patients who reached the TSH suppression standard in the hemithyroidectomy group was higher than in the total thyroidectomy group. After TSH suppression treatment, serum FT4 levels were increased in both total thyroidectomy and hemithyroidectomy. The difference in serum TSH, FT3, and FT4 levels was associated with different genotypes, and patients with high cytosine cytosine (CC) genotypes may have difficulty meeting the TSH suppression criteria.

Conclusions: Patients who underwent total thyroidectomy exhibited higher postoperative serum FT4 levels than patients in the hemithyroidectomy group after TSH suppression therapy. The Thr92Ala polymorphism of type 2 deiodinase (D2) was associated with TSH suppression therapy.