Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2016) 41 GP227 | DOI: 10.1530/endoabs.41.GP227

ECE2016 Guided Posters Thyroid Cancer (10 abstracts)

Is ultrasensitive Tg measurement capable of substituting for Tg measurement after rhTSH stimulation in evaluation of effectiveness of radioiodine ablation in patients with differentiated thyroid cancer

Aldona Kowalska , Danuta Gasior-Perczak , Iwona Palyga , Tomasz Trybek & Anna Sluszniak


Holycross Cancer Centre, Kielce, Poland.

Introduction: Undetectable concentration of Tg after rhTSH stimulation (Tg/rhTSH) is one of the most important criteria in evaluating the effectiveness of radioiodine ablation in patients with differentiated thyroid cancer (DTC) treated with 131I.

Aim: To evaluate the possibility of using L-T4 suppression treatment (Tg/L-T4) measurements by the ultrasensitive method TRACE (immunofluorescence method) with the KRYPTOR analyzer instead of the Tg/rhTSH measurements with the chemiluminescent immunoassay (CLIA).

Material: The study was performed on 34 consecutive DTC patients after surgery and adjuvant treatment with 131I, referred for evaluation of ablation effectiveness 9 months after 131I treatment.

Method: Tg measurement was performed in patients during L-T4 treatment at two time points: before administration of rhTSH and 5 days after the first injection, using both tests: Tg detection with CLIA (analytical sensitivity 0.2 ng/ml and functional sensitivity of 0.9 ng/ml) and Tg by TRACE (analytical sensitivity of 0.09 ng/ml and functional sensitivity 0.15 ng/ml).

Results: Tg/L-T4 concentration in all patients was <1.0 ng/ml in the CLIA assay, and in the range of <0.09 ng/ml – 0.354 ng/ml in the TRACE assay. After rhTSH stimulation, Tg concentration of <1.0 ng/ml (excellent treatment response) as measured by CLIA was found in 30/34 patients. In four patients, however, Tg/rhTSH was in the range of 1.0–10.0 ng/ml (1.02, 1.83, 2.2, 9.24 ng/ml – indeterminate response). In the latter group Tg/L-T4 by TRACE was 0.09 ng/ml; 0.1141 ng/ml; 0.1629 ng/ml; 0.09 ng/ml.

Conclusions: 1 None of the four cases with indeterminate response to ablation showed elevated Tg/L-T4 concentrations according to the ultrasensitive TRACE assay.

2 Results in our trial group do not entitle us to recommend determinations of Tg/L-T4 with the TRACE method instead of the Tg/rhTSH in assessing the ablation efficacy.

3 It is necessary to validate the method on a larger group of patients.

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