ORIGINAL ARTICLE
ISSN (print) 1869-3482
ISSN (online) 1869-3474
Response Prediction of Altered Thyroglobulin Levels After Radioactive
Iodine Therapy Aided by Recombinant Human Thyrotropin in Patients
with Differentiated Thyroid Cancer
Minchul Song
1
&
Subin Jeon
1
&
Sae-Ryung Kang
1
&
Zeenat Jabin
1
&
Su Woong Yoo
1
&
Jung-Joon Min
1
&
Hee-Seung Bom
1
&
Sang-Geon Cho
2
&
Jahae Kim
2
&
Ho-Chun Song
2
&
Seong Young Kwon
1
Received: 22 February 2018 / Revised: 16 April 2018 /Accepted: 23 May 2018
#
Korean Society of Nuclear Medicine 2018
Abstract
Purpose Thyroglobulin (Tg) may be released from damaged residual thyroid tissues after radioactive iodine (RAI) therapy in
patients with differentiated thyroid carcinoma (DTC). We investigated whether altered levels of serum Tg after recombinant
human thyrotropin (rhTSH)-aided RAI therapy could be a prognostic marker in patients with DTC.
Methods We evaluated 68 patients who underwent RAI therapy after total thyroidectomy. Serum Tg levels were measured just
before RAI administration (D0Tg) and 7 days after RAI therapy (D7Tg). Patients with a D0Tg level greater than 2.0 ng/mL were
excluded to more precisely evaluate the injury effect of RAI in small remnant tissues. The ratioTg was defined as the D7Tg level
divided by that on D0Tg. The therapeutic responses were classified as acceptable or non-acceptable. Finally, we investigated
which clinicopathologic parameters were associated with therapeutic response.
Results At the follow-up examination, an acceptable response was observed in 50 patients (73.5%). Univariate analysis revealed
significant differences in N stage (P = 0.003) and ratioTg (acceptable vs. non-acceptable responses, 21.9 ± 33.6 vs. 3.8 ± 6.5; P =
0.006). In multivariate analysis, only ratioTg significantly predicted an acceptable response (odds ratio 1.104; 95% confidence
interval 1.005–1.213; P = 0.040). A ratioTg above 3.5 predicted an acceptable response with a sensitivity of 66.0%, specificity of
83.3%, and accuracy of 70.6% (area under the curve = 0.718; P =0.006).
Conclusions Altered levels of serum Tg after RAI therapy, calculated as the ratioTg (D7Tg/D0Tg), significantly predicted an
acceptable response in patients with DTC.
Keywords Differentiated thyroid carcinoma
.
Radioactive iodine therapy
.
Recombinant human thyrotropin
.
Thyroglobulin
.
Therapeutic response
Introduction
Thyroglobulin (Tg) is a representative biomarker used to
predict outcome in patients with differentiated thyroid car-
cinoma (DTC) who have undergone total thyroidectomy
followed by radioactive iodine (RAI) therapy [1–8]. High
levels of stimulated Tg before RAI therapy aided by
thyroid hormone withdrawal (THW) were reported to pre-
dict a poor prognosis [2–5].
In DTC patients who received RAI therapy prepared with
recombinant human thyrotropin (rhTSH), stimulated Tg mea-
sured before or after RAI therapy (72 h after the final injection
of rhTSH) could be also used as a prognostic marker [7, 8].
However, rhTSH-stimulated Tg levels before RAI therapy
could be underestimated because 72 h after the second injec-
tion of rhTSH corresponds to peak serum Tg levels [9].
rhTSH-stimulated Tg levels checked 72 h after the second
injection could be overestimated through the addition of Tg
released from damaged residual thyroid tissues after RAI-
induced cellular injury [10–13].
Several studies have suggested that altered levels of serum
Tg after THW-aided RAI therapy could predict the prognosis
of patients with DTC [1, 3, 5, 6]. Therefore, we investigated
* Seong Young Kwon
suninocean@gmail.com
1
Department of Nuclear Medicine, Chonnam National University
Hwasun Hospital, 322 Seoyang-ro, Hwasun-eup,
Hwasun-gun, Jeollanam-do 58128, South Korea
2
Department of Nuclear Medicine, Chonnam National University
Hospital, 42 Jebong-ro, Dong-gu, Gwangju 61469, South Korea
Nuclear Medicine and Molecular Imaging
https://doi.org/10.1007/s13139-018-0528-7
@Phil_Robichaud
@deepthiw
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