Clinical Significance

Thyroglobulin is present in the serum of normal healthy individuals and can be elevated in numerous disorders which disrupt thyroid tissue. Elevated circulating levels of Thyroglobulin have been reported in a number of thyroid conditions including Hashimoto's disease, Graves' disease, thyroid adenoma, subacute thyroiditis and thyroid carcinoma.

Thyroid cancer is a relatively common form of cancer. It is not generally highly malignant, and normal life span can be obtained with appropriate follow-up and treatment. Females are affected 2 to 3 times more frequently than males. Thyroglobulin has become a useful tool in the follow-up of patients with differentiated thyroid carcinoma (i.e. papillary-follicular or follicular carcinoma of the thyroid). The thyroid is the only source of Thyroglobulin; therefore, the serum Thyroglobulin level will drop to a very low or undetectable level after total or near-total thyroidectomy and successful radioiodine ablation of the residual thyroid tissue. A rise in the serum level of Thyroglobulin points to the recurrence of the disease. Thyroglobulin levels in patients who have undergone only a partial thyroidectomy will retain measurable levels of Thyroglobulin, depending on how much tissue is remaining after surgery. These patients can be monitored by Thyroglobulin measurement, but the post-surgical Thyroglobulin level must be taken into account.

A limiting factor in the use of serum thyroglobulin measurements is the presence of thyroglobulin autoantibodies found in some patients. These antibodies may interfere with the immunoassay used to measure thyroglobulin and can cause false high or false low values. It is important to determine the levels of thyroglobulin autoantibodies in patients requiring serum Thyroglobulin measurements