Role of serum thyroglobulin levels in differentiating hyperthyroidism and thyrotoxic phases of thyroiditis

Abstract

ABSTRACT Background: Thyroid hormones are crucial for growth, brain development, reproduction, and the regulation of energy metabolism. The iodoglycoprotein thyroglobulin (Tg) plays a critical role in allowing the thyroid gland to synthesize the thyroid hormones T3 and T4 in humans. Thyrotoxicosis has a wide range of etiologies, symptoms, and therapeutic options. Therefore, a precise diagnosis is necessary for effective treatment. In addition to a thyroid function test (TFT), evaluation for identifying common causes of thyrotoxicosis also includes a thyroid ultrasound that measures thyroidal blood flow, a radioactive iodine uptake test, a thyrotropin receptor autoantibody (TRAb) test, and a 99mTc pertechnetate scan. We hypothesize that Tg levels may be elevated in hyperthyroidism, which includes Graves’ disease (GD) and toxic multinodular goiter (TMNG), as there is an increase in thyroid synthesis and secretion. In thyrotoxic phases of thyroiditis, Tg levels could be normal. Objective: This study aimed to evaluate serum Tg levels in differentiating hyperthyroid and thyrotoxic phases of thyroiditis. Methods: In this study, 30 subjects with newly detected untreated thyrotoxicosis were evaluated. Serum Tg, TFT, TRAb, Anti-TPO, and technetium scan were done. Results: Our study results revealed that the Median Tg was highest in the subjects with toxic nodular goiter (356 ng/ml), followed by GD (150.40 ng/ml); those with subacute thyroiditis had the lowest Tg level (7.42 ng/ml); the differences in median Tg levels across the three groups were also statistically significant (P < 0.01). TRAb was significantly higher in people with GD in comparison to TMNG and thyroiditis. In addition, GD patients with a higher titter value of TRAb have elevated levels of Tg. Conclusion: Serum Tg levels can be utilized as a potent marker to distinguish between different types of thyrotoxicosis.