Recent studies have shown that thyroglobulin (Tg) concentration is a useful tumor marker in follow-up of differentiated thyroid cancer (DTC) patients after thyroidectomy and subsequent radioiodine (I-131) therapy. However, its role is controversial after total or near-total thyroidectomy before the first I-131 ablative treatment. So, we used thyroid-stimulating hormone (TSH) levels to normalize predictive values of Tg for DTC.