Thyroglobulin is elevated in three types of thyroid disorders: goiter and thyroid hyperfunction, inflammation or physical injury to the thyroid, and differential thyroid tumors.

Those thyroid cancer patients who have no remaining thyroid tissue, following surgery and/or irradiation, would not be expected to have a source of thyroglobulin. Thyroglobulin then is a tumor marker useful to assess the presence of residual papillary-follicular carcinoma of thyroid, following resection, including tumors which fail to concentrate radioiodine. High values are found with many instances of tumor dissemination; thus, thyroglobulin assays are used to monitor postoperative thyroid carcinoma patients. Such assays are best used in concert with total body scans. Possibly it will be useful in patients with bone metastases in whom the primary site is unknown.

Low or undetectable levels in thyrotoxicosis are a clue to thyrotoxicosis factitia (surreptitious use of thyroid hormone). The assay may be useful to support a diagnosis of subacute thyroiditis.

The absence of thyroglobulin from the serum of neonates suggests congenital athyreosis.

Thyroglobulin is useful in the management but not diagnosis of differentiated thyroid carcinomas. Thyroglobulin may prove useful as an indicator of T₄ therapy in patients with solitary nodules.