Unstimulated high sensitive thyroglobulin measurement predicts outcome of differentiated thyroid carcinoma

Abstract

Background: Thyroglobulin (Tg) measurement following thyrotropin (TSH) stimulation is used in the follow-up of patients with differentiated thyroid carcinoma (DTC). However, high-sensitive assays allow accurate measurement of serum Tg even without TSH stimulation. Here, we prospectively evaluated the impact of unstimulated high-sensitive Tg measurement in early and long-term outcome of patients with DTC. Methods: One hundred and ninety five patients affected with DTC were evaluated. Six months after thyroid ablation (i.e., thyroidectomy plus radioiodine) serum Tg was measured during TSH-suppressive thyroxine (T4) treatment (onT4-Tg). Patients with undetectable onT4-Tg and negative neck ultrasound (US) were considered disease free and onT4-Tg was measured every 12 months for a mean follow-up of 6.8 (4.7-8.9) years. Patients with an increase in onT4-Tg underwent specific diagnostic work-up and appropriate treatment if necessary. Results: Four patients showed recurrence at first follow-up visit with a corresponding increase in onT4-Tg concentrations (sensitivity 100%). Three patients had false positive onT4-Tg measurement (specificity 98%) with a spontaneous decrease within 3-6 months in all cases (specificity 100%). Three of 188 patients with undetectable serum onT4-Tg at first follow-up showed recurrence later with an increase in onT4-Tg as the first (ns2) or unique (ns1) sign of relapse (sensitivity 100%). Among 185 disease-free patients in

Basal Serum Thyroglobulin Measured by a Second-Generation Assay Is Equivalent to Stimulated Thyroglobulin in Identifying Metastases in Patients with Differentiated Thyroid Cancer with Low or Intermediate Risk of Recurrence

“…However, over the last decade, Tg2G assays that present an FS tenfold greater, in the order of 0.05-0.1 ng/ml, have been developed and validated, and these assays are now routinely used in laboratories worldwide [12,13,14,15,16,17,18,19,20,21]. These studies have shown that when a second-generation assay is employed for Tg measurement, undetectable serum b-Tg has the same predictive value as s-Tg.…”

“…The authors of these studies analyzed a total of 953 patients, mainly belonging to the group of patients with a low risk of recurrence, using Tg2G assays (0.1 or 0.2 ng/ml), and only 19 of the 953 patients showed evidence of recurrent disease (16 of them seen on neck US). The authors concluded that these patients with undetectable b-Tg rarely have s-Tg greater than 1.0 or 2.0 ng/ml (1.7%) and that they rarely present with metastasis (1.3%) [12,13,14,15,16,17,18,19,20,21]. …”

“…These studies have shown that in low-risk DTC patients, when these second-generation Tg (Tg2G) assays are used (FS 0.05-0.1 ng/ml), b-Tg is correlated with WD-Tg and rhTSH-Tg [14,15,16,17,18,19,20,21]. The purpose of the present study was to prospectively evaluate a cohort of patients treated for DTC with a low or intermediate risk of recurrence using a Tg2G assay during a long-term follow-up.…”

Papillary thyroid microcarcinoma

“…Некоторые авторы пишут об отсут-ствии необходимости измерения стимулированного ТГ, так как, по их данным, неопределяемый базаль-ный ТГ (<0,1 нг/мл) дает необходимую информацию [82][83]. В клинической практике при базальном уровне ТГ <0,1 нг/мл и отсутствии остаточной ткани ЩЖ по данным УЗИ шеи пациенты могут быть от-несены к группе с ремиссией заболевания.…”

Innovation in the Post-Surgical Menagment of Differentiated Thyroid Carcinoma

“…Recently, new methods for serum Tg measurement with functional sensitivity below 0.1 ng/ml became available. Using these assays some authors reported that an undetectable basal serum Tg (<0.1 ng/ml) may give the same information of a stimulated serum Tg value, thus avoiding the need for Tg stimulation (13)(14)(15)(16)(17)(18)(19)(20). However, the higher negative predictive value (NPV) of these tests is at the expenses of a very low specificity and positive predictive value (PPV) and the risk is to expose large numbers of patients, probably free of disease, to extensive testing and/or unnecessary treatment.…”