ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2019) 63 P766 | DOI: 10.1530/endoabs.63.P766

Is the determination of rTSH estimulated thyroglobulin necessary for long term management in patients with differentiated thyroid carcinoma?

Miriam Cozar1, Ana Romero1, Suset Dueñas1, Inmaculada Domínguez2 & Elena Navarro1


1Unit of Clinical Management of Endocrinology and Nutrition, University Hospital Virgen del Rocio., Seville, Spain; 2Unit of Laboratory of Hormones, University Hospital Virgen del Rocio., Seville, Spain.


Introduction: In clinical practice guidelines for differentiated thyroid cancer (DTC) it has been proposed to perform thyroglobulin (Tg) stimulated by rTSH determination 6–12 months after initial therapy in patients with low or intermediate risk, in order to establish the absence of disease. The use of ultrasensitive Tg assays could avoid the need of stimulation to establish the absence of disease.

Objectives: To evaluate the usefulness of the determination of rTSH-stimulated Tg in patients with low and intermediate risk CDT treated with I131 and with undetectable ultrasensitive Tg (<0.04 ng/ml) under levotiroxine suppressive therapy.

Material and methods: The values of stimulated Tg after rTSH were evaluated in patients diagnosed of low and intermediate risk CDT treated with I 131, that presented undetectable Tg and negative anti-thyroglobulin antibodies (AbTg) after 6 months of initial treatment. From October 2016 to December 2017 an ultrasensitive Tg assay was used, in which it was considered undetectable <0.04 ng/ml (Group A) compared to a control group (Group B) from July 2015 to September 2016, in which the determination of Tg was made by a lower functional sensitivity test (considering Tg <0.20 ng/ml undetectable). High-risk CDT or positive AbTg patients were excluded.

Results:

Group A (Ultrasensitive Tg) p NSGroup B (Control group) p NS
Total patients35 (47.9%)38 (52.1%)
Women/men24 (68.6%)/ 11 (31.4%)33 (86.8%)/ 5 (13.2%)
Age at diagnosis48.8±14.4 years44.5±13.2 years
Type of tumor Papillary/Follicular32 (91.4%)/ 3 (8.6%)34 (89.5%)/ 4 (10.5%)
Extrathyroid extension4 (11.4%)1 (2.6%)
Presence of adenopathies4 (11.4%)1 (2.6%)
Size
T113 (37.2%)15 (39.5%)
T219 (54.3%)17 (44.7%)
T33 (8.6%)6 (15.8%)
Normal / altered ultrasound34 (97.1%)/1 (2.9%) ganglion38 (100%)/0
Estimulated Tg after rTSH
< 1 ng/ml35 (100%) 36 (94.7%)
>1 ng/ml02 (5.3%)
Response to treatment
Excellent33 (94.3%)36 (94.7%)
Undetermined1 (2.9%)2 (5.3%)
Pending classification1 (2.9%)0
Follow-up time23.7±9.3 months.36.7±6.8 months.

Conclusions

- The determination of ultrasensitive Tg stimulated with rTSH in patients with low and intermediate risk CDT provides little additional information, so in this group of patients the determination of ultrasensitive Tg in suppressive treatment could be an adequate method to establish absence of disease.

- There were no statistically significant differences between both groups regarding the distribution of stimulated Tg greater than 1.

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