Low thyroglobulin concentrations after thyroidectomy increase the prognostic value of undetectable thyroglobulin levels on levo-thyroxine suppressive treatment in low-risk differentiated thyroid cancer

Recombinant human TSH-stimulated thyroglobulin (Tg) levels (rhTSH-Tg) are sufficient for early follow-up of low-risk differentiated thyroid cancer (DTC) patients after thyroidectomy and radioiodine (131I) remnant ablation (RAI). Serum Tg levels at the time of remnant ablation (ablation-Tg) is thought to be related with rhTSH-Tg and may be predictive of recurrent disease. During long-term follow-up, Tg levels on levo-T4 (L-T4) suppressive treatment (suppressive-Tg) is sufficiently sensitive to avoid further evaluations in patients with undetectable rhTSH-Tg. The aim of our study was to verify whether, in a subgroup of low-risk DTC patients, the association of low ablation-Tg levels (<10 microg/l) with undetectable suppressive-Tg concentrations has a sufficient negative predictive value (NPV) for recurrence of disease, leading to avoid rhTSH testing.