Serum thyroglobulin and iodine-131 whole-body scan in the diagnosis and assessment of treatment for metastatic differentiated thyroid carcinoma.
Because of the limitations of periodic 131I whole-body scans, including suspension of substitution therapy, questionable sensitivity and low yield in detecting metastases in patients who have undergone thyroidectomy, serum thyroglobulin and 131I whole-body scans were evaluated for sensitivity in detecting local, regional or distant metastases in 261 patients with differentiated thyroid carcinoma after total thyroidectomy and ablation.


METHODS
A noncompetitive immunoradiometric assay was used for serum thyroglobulin determination. An 131I whole-body scan was obtained after replacement therapy had been suspended for 6 wk or when TSH reached levels higher than 50 microU/ml. In patients who underwent radiological procedures with iodinated contrast media, the waiting period before the 131I whole-body scan was no less than 10 wk.


RESULTS
Of the 58 patients with proven metastases who were followed for 12 yr (mean 7 +/- 3.3 yr), 51 (88.4%) had high serum thyroglobulin assays performed while under full replacement therapy and 32 (55%) showed clear 131I whole-body scan localization. There were no instances of positive whole-body scans and negative serum thyroglobulin.


CONCLUSIONS
In patients treated with 131I, serum thyroglobulin assay was an excellent method to assess treatment. Patients with metastatic disease and negative whole-body scans with or without serum thyroglobulin exhibited a trend toward higher mortality. This trend may also indicate that the lack of 131I trapping and low thyroglobulin is a sign of metabolic dedifferentiation of otherwise histologically differentiated thyroid tumors.
Lubin
E
E
Department of Nuclear Medicine, Beilinson Medical Center, Petah Tiqva, Israel.
Mechlis-Frish
S
S
Zatz
S
S
Shimoni
A
A
Segal
K
K
Avraham
A
A
Levy
R
R
Feinmesser
R
R
D018263:Adenocarcinoma, Follicular / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D000328:Adult; D000368:Aged; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D011877:Radionuclide Imaging; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy
D007457:Iodine Radioisotopes; D013954:Thyroglobulin