Additional value of a high sensitive thyroglobulin assay in the follow-up of patients with differentiated thyroid carcinoma.

Abstract

Thyroglobulin (Tg) is an excellent tumour marker, as detectable or increasing Tg levels are highly indicative of persistent or recurrent differentiated thyroid carcinoma (DTC). The clinical value of a highly sensitive (hs)-Tg assay in patients with DTC has not yet been established. The aim of this study was to investigate the additional value of unstimulated hs-Tg measurements (Tg-on) compared to stimulated IRMA-Tg measurements (Tg-off) in the follow-up of patients with DTC. We retrospectively studied patients treated for DTC between 2006 and 2013 and compared hs-Tg and IRMA-Tg measurements. The study group consisted of 99 DTC patients in remission; Tg-on was measured 3 months after remnant ablation and Tg-off 6 months after ablation. In the study group, 44 patients showed a hs-Tg-on <0·15 μg/l (functional sensitivity); of these, 43 had an IRMA-Tg-off measurement <1·0 μg/l, resulting in a negative predictive value of 97·7% and a positive predictive value of 56·4%. The hs-Tg-on measurement is able to predict patients with an IRMA-Tg-off <1·0 μg/l, and therefore decreases the need for Tg stimulation after ablation.