Based on our data we conclude that pre-ablative onT4-Tg is a prognostic marker and should be used instead of pre-ablative TSH-stimulated Tg measurement when rhTSH-aided radioiodine ablation is done.

Our preliminary data need further confirmation on larger groups of patients, but seem to indicate that onT(4)-TG assay by a high-sensitivity method combined with neck US may avoid rhTSH stimulation in low-risk DTC patients after surgery and radioiodine thyroid ablation.

A negative MIBI scan in a cold nodule accurately excludes malignancy when US-FNAC is reported as nondiagnostic. This avoids the need for more invasive diagnostic procedures (ie, surgery) and positively influences the cost-effectiveness profile. A MIBI scan may be performed by acquiring images 30 minutes after tracer administration alone. Histology is still necessary to distinguish benign from malignant disease in a MIBI-positive nodule but unnecessary surgery could have been reduced from 71 to 8 cases in our series.

A reliable Tg(t(1/2)) estimation could be obtained by a simplified formula requiring only 2 postsurgery Tg measurements (24 and 120 hours, respectively).

Background: Thyroglobulin (Tg) measurement following thyrotropin (TSH) stimulation is used in the follow-up of patients with differentiated thyroid carcinoma (DTC). However, high-sensitive assays allow accurate measurement of serum Tg even without TSH stimulation. Here, we prospectively evaluated the impact of unstimulated high-sensitive Tg measurement in early and long-term outcome of patients with DTC. Methods: One hundred and ninety five patients affected with DTC were evaluated. Six months after thyroid ablation (i.e., thyroidectomy plus radioiodine) serum Tg was measured during TSH-suppressive thyroxine (T4) treatment (onT4-Tg). Patients with undetectable onT4-Tg and negative neck ultrasound (US) were considered disease free and onT4-Tg was measured every 12 months for a mean follow-up of 6.8 (4.7-8.9) years. Patients with an increase in onT4-Tg underwent specific diagnostic work-up and appropriate treatment if necessary. Results: Four patients showed recurrence at first follow-up visit with a corresponding increase in onT4-Tg concentrations (sensitivity 100%). Three patients had false positive onT4-Tg measurement (specificity 98%) with a spontaneous decrease within 3-6 months in all cases (specificity 100%). Three of 188 patients with undetectable serum onT4-Tg at first follow-up showed recurrence later with an increase in onT4-Tg as the first (ns2) or unique (ns1) sign of relapse (sensitivity 100%). Among 185 disease-free patients in