A sensitive RT-PCR assay amplifying thyroid-specific mRNAs such as TG or thyroid peroxidase (TPO) may be utilized for the early detection of DTC recurrence and thus may have important therapeutic and prognostic implications. In fact, 2 recent reports have shown the clinical usefulness of the RT-PCR detection of TG, TPO, and ret /PTC in the follow-up of DTC (Ringel et al, 1998; Tallini et al, 1998) . For example, TG mRNA in peripheral blood became detectable earlier than serum TG in a case of recurrent thyroid papillary carcinoma. Recently, Ringel et al have reported the clinical usefulness of the real-time quantitative measurement of TG mRNA in the peripheral blood of the patients with DTC. In their report, however, they did not use an appropriated internal reference such as glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA .