title: Critical evaluation of serum thyroglobulin levels and I-131 scans in post-therapy patients with differentiated thyroid carcinoma: concise communication.
abstract: Serum thyroglobulin measurements by radioimmunoassay were performed in the follow-up of 68 patients with differentiated thyroid carcinoma undergoing I-131 total-body scans following surgery and/or I-131 therapy. Of 12 patients with distant metastases demonstrated by I-131 scan, thyroglobulin levels were elevated (greater than 60 ng/ml) in nine (75%); the remaining 25% either ranged between 20 and 60 ng/ml or were below 20 ng/ml in spite of having functional metastases. Of six patients with only regional lymph-node metastases demonstrated by I-131 scan, only one (16%) had an elevated thyroglobulin level, while two fell in the 20-60 ng/ml range and three were below 20 ng/ml. Of the remaining patients with no metastatic disease demonstrable by I-131 scan, three (6%) had elevated thyroglobulin levels. These patients were subsequently found to have metastatic disease by other criteria. These results suggest caution in the use of thyroglobulin levels as a replacement for I-131 scans in the follow-up of differentiated thyroid carcinoma. Based on our study, however, the two methods complement each other to achieve maximum sensitivity and reliability.
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000628:therapy; D000328:Adult; D000368:Aged; D002291:Carcinoma, Papillary / Q000175:diagnosis* / Q000628:therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay; D011933:Reagent Kits, Diagnostic; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000628:therapy
chemical_list: D007457:Iodine Radioisotopes; D011933:Reagent Kits, Diagnostic; D013954:Thyroglobulin