Relationship Between Post-surgery Serum Tg and PT-WBS results The patients with positive PT-WBS showed higher onT4-Tg (0.617±0.445 vs 0.341±0.402 ng/mL), rhTSH-Tg (2.150±1.249 vs 0.664±0.803 ng/mL) and offT4-Tg (4.417±2.136 vs 1.195±1.485 ng/mL) levels as compared with patients with negative scan. Among 14 patients with undetectable onT4-Tg (i.e. ≤0.2 ng/mL) none had positive PT-WBS neither recurrences at 12-months restaging. Additionally, none of these patients showed stimulated Tg values more than 0.4 ng/mL and 1.0 ng/mL after rhTSH stimulation and T4 withdrawal, respectively. Viceversa, among 14 patients with onT4-Tg levels more than 0.2 ng/mL, 6 had positive PT-WBS (onT4-Tg: 0.3 to 1.4 ng/mL) and 3 showed DTC recurrences at 12 months restaging (onT4-Tg: 0.9 to 1.7 ng/mL). Consequently, the onT4-Tg levels predicts PT-WBS results with a 100% negative and 43% positive predictive values, respectively. Additionally onT4-Tg levels of 0.9 ng/mL or more predicts 12-months recurrences with 100% negative and 60% positive predictive value. In comparison, 1.0 ng/mL or higher offT4-Tg values predicted PT-WBS results and 12-months restaging with 94% and 100% negative and 45% and 27% positive predictive value, respectively.