Thyroglobulin antibodies are directed at the protein the thyroid uses to store hormone before releasing it. They are a second marker of an immune process in the gland, and they also matter as an interference check when thyroglobulin itself is measured after thyroid cancer treatment. The test says nothing about how much hormone the gland is making.
No readings for this marker yet.
Raised levels occur in autoimmune thyroiditis and Graves' disease, often alongside TPO antibodies, and in a smaller share of people with unremarkable thyroid function. Isolated positivity without TPO antibodies is less specific and is common in people who never develop thyroid disease. In follow-up after thyroid cancer, a detectable level chiefly signals that thyroglobulin results may read falsely low. Any positive result is interpreted by a doctor in the context of the rest of the panel.
Assays and cut-offs vary widely between laboratories, so values from different labs should not be compared directly, and biotin supplements can distort the measurement. The result is stable across the day and unaffected by meals or by thyroid medication taken that morning. It is read together with TPO antibodies and with TSH and free thyroxine, and, in cancer follow-up, always in the same sample as thyroglobulin.
Reference ranges are general adult values and depend on lab, assay, age and sex. For orientation, not diagnosis — discuss results with your doctor.