What does it mean when thyroid globulin (Tg) levels are low?

Thyroid globulin (TG) is a protein secreted by thyroid follicular epithelial cells. A low TG level typically results from thyroid surgery, iodine deficiency, or thyroid disorders. Detailed explanations are as follows: TG levels reflect the structural integrity of the thyroid gland. Causes of low thyroid globulin include:

1. Thyroid surgery: Surgical intervention damages the thyroid gland, leading to reduced TG production. With appropriate postoperative care and dietary adjustments, TG levels may gradually improve.

2. Iodine deficiency: In some cases, low TG levels stem from insufficient iodine intake. This can be corrected by increasing consumption of iodine-rich foods—such as kelp and sea fish—and using iodized salt regularly.

3. Thyroid disease: Conditions such as thyroiditis can damage thyroid follicular epithelial cells, thereby lowering TG levels. Treatment may include antithyroid medications (e.g., methimazole); in certain cases, radioactive iodine-131 therapy may be indicated.