Thyroid cancer recurrence is mainly based on thyroglobulin, while thyroglobulin antibodies need to be detected, and a combination of imaging and pathology is needed to diagnose recurrence.
Thyroglobulin (Tg) should be undetectable in the blood of people who have undergone surgery for thyroid cancer and complete removal of the thyroid gland after radionuclide therapy, and Tg should be at low levels in people who have not undergone total thyroidectomy.
Thyroid stimulating hormone (TSH) suppression therapy with levothyroxine is required after thyroid cancer surgery. Tg should be <0.2ng/ml in the suppressed state and <1ng/ml when levothyroxine is discontinued or in the TSH-stimulated state.
A Tg >1ng/ml suggests the possibility of thyroid cancer recurrence or tissue retention. If Tg >10ng/ml in lobectomized patients, it suggests possible recurrence of thyroid cancer.
Thyroglobulin antibody (TgAb) binds to Tg and affects the Tg test result, so both Tg and TgAb levels should be monitored.
Thyroid cancer recurrence cannot be diagnosed based on Tg alone, but usually requires neck ultrasound, enhanced CT, and pathologic biopsy.
Patients are advised to undergo regular Tg and imaging monitoring after thyroid cancer surgery for early detection and treatment of recurrence and other conditions.