TG and metastatic neoplasm: However, considering both all enrolled patients and serum a-Tg values ≥ 10 ng/ml as suspicious for metastatic disease, the overall sensitivity, specificity, accuracy, PPV and NPV of serum a-Tg values in detecting metastatic patients were 31.7%, 96%, 86.6%, 56.5% and 89.3%, respectively.