[Thyroglobulin as a tumor marker and thallium scintigraphy for the course control of differentiated thyroid cancer]

The usefulness of measurement of serum thyroglobulin (TG) concentration and whole body 201-thallium scintigraphy for follow-up were evaluated prospectively in 80 patients with differentiated thyroid cancer. All patients had undergone thyroidectomy and 131-iodine ablation. In 74 patients without residual thyroid tissue and a negative whole body thallium and/or iodine scan, the TG concentration in plasma was undetectable. In 5 of the remaining 6 patients, TG was measurable while the patient was receiving T3 therapy and undetectable in one. After 1 and 2 weeks off T3, TG increased in all 6 patients in parallel with TSH. Of 5 patients with abnormal 201Tl scintigraphy, 2 have residual local tissue and 3 distant metastases. Of these cases, 131I scintigraphy detected metastases in only one and local tissue in 2 patients. It is concluded that 1. TG is TSH-dependent and increases after withdrawal of T3 replacement therapy. 2. TG measurements under T3 replacement therapy are less sensitive than measurements made after withdrawing T3. 3. 201Tl scintigraphy can replace 131I scintigraphy in follow-up controls. 4. The combination of serum TG and 201Tl scintigraphy seems to be superior to either one alone and can be performed while patient is on replacement therapy.