title: Influence of the thyroid remnant in the elevation of the serum thyroglobulin after thyroidectomy in differentiated thyroid carcinoma. Importance of the diagnostic iodine total-body scanning.
abstract: OBJECTIVE
  Stimulated thyroglobulin (Tg) and (131)I total-body scan (TBS) have been the mainstays of differentiated thyroid carcinoma (DTC), but now diagnostic TBS has been eliminated from some follow-up protocols. Nevertheless, Tg can be negative in the presence of thyroid tissue, and moderately elevated Tg poses management problems. The purpose of this study was to check how many patients have Tg negative but visible thyroid tissue and if diagnostic TBS could be clinically useful.
  
  
  METHODS
  Retrospective review of 317 exams (stimulated Tg and TBS) of 128 patients with DTC. Patients with high-grade criteria and/or positive autoantibodies are excluded. Tg is considered positive if higher than the sensitivity level of the technique. TBS is positive if thyroid remnant, lymphatic node or metastases are detected. Results are classified in Tg and TBS concordant or discordant.
  
  
  RESULTS
  Discordant (131)I TBS and Tg were found in 74/317 studies (23.3%), 48 (65%) being TBS positive and Tg negative. None of 128 patients had a first post-surgery negative scan, but 13 (10%) were Tg negative, even two patients with lymph node uptake. One year after radioiodine treatment, 26 out of 115 patients (initially Tg and TBS concordant positive) showed Tg negative and TBS still positive due to cervical remnants (20 patients), lymph node uptake (one) and metastasis (five); 20 patients remained Tg and TBS positive, but 14 of them only showed thyroid remnants.
  
  
  CONCLUSIONS
  We propose to perform periodic diagnostic TBS to improve Tg specificity, at least while neck thyroid activity is detected, even if Tg is negative.
authors.affiliation: Hospital Universitario Dr. Peset-Medicina Nuclear, Avda. Gaspar Aguilar, 90, Valencia, Valencia, 46017, Spain. caballero_eli@gva.es
authors.forename: Elisa
authors.initials: E
authors.lastname: Caballero-Calabuig
authors.forename: Carmen
authors.initials: C
authors.lastname: Cano-Terol
authors.forename: Ramón
authors.initials: R
authors.lastname: Sopena-Monforte
authors.forename: Dolores
authors.initials: D
authors.lastname: Reyes-Ojeda
authors.forename: Pedro
authors.initials: P
authors.lastname: Abreu-Sánchez
authors.forename: José
authors.initials: J
authors.lastname: Ferrer-Rebolleda
authors.forename: Pablo
authors.initials: P
authors.lastname: Sopena-Novales
authors.forename: Carmen
authors.initials: C
authors.lastname: Plancha-Mansanet
authors.forename: Jesús
authors.initials: J
authors.lastname: Félix-Fontestad
mesh_terms: D000293:Adolescent; D000328:Adult; D016477:Artifacts; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013954:Thyroglobulin / Q000097:blood*; D013961:Thyroid Gland / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000601:surgery*; D013964:Thyroid Neoplasms / Q000097:blood / Q000000981:diagnostic imaging* / Q000601:surgery*; D013965:Thyroidectomy; D051598:Whole Body Imaging / Q000379:methods*
chemical_list: D007457:Iodine Radioisotopes; D013954:Thyroglobulin