These associations remained significant after multivariable adjustment and were supported by correlations between Tg and SPINA-GD, a model-based index of thyroid function reflecting deiodinase activity, with similar findings observed in patients with autoimmune hyperthyroidism.<h4>Conclusion</h4>These findings suggest that serum Tg levels may reflect biochemical features consistent with T3 predominance in autoimmune hyperthyroidism and have potential clinical utility in characterizing disease pathophysiology. This evidence concerns the gene TG and Graves disease.