Exp Clin Endocrinol Diabetes 2010; 118(7): 393-399
DOI: 10.1055/s-0029-1225350

© J. A. Barth Verlag in Georg Thieme Verlag KG Stuttgart · New York

Thyroid Remnant Dose: 124I-PET/CT Dosimetric Comparison of rhTSH versus Thyroid Hormone Withholding Before Radioiodine Remnant Ablation in Differentiated Thyroid Cancer

L. S. Freudenberg1 , C. Frömke3 , T. Petrich2 , R. J. Marlowe4 , W. W. Koska1 , W. Brandau1 , E. G. Eising1 , E. J. Knust1 , A. Bockisch1 , W. Jentzen1
  • 1Department of Nuclear Medicine, University of Duisburg/Essen, Essen, Germany
  • 2Department of Nuclear Medicine, Medizinische Hochschule Hannover, Hannover, Germany
  • 3Department of Statistics, Medizinische Hochschule Hannover, Hannover, Germany
  • 4Medical Writer and Editor, Spencer-Fontayne Corporation, Jersey City, NJ, USA
Further Information

Publication History

received 15.01.2009 first decision 06.05.2009

accepted 25.05.2009

Publication Date:
23 October 2009 (eFirst)


Aim: Recombinant human thyroid-stimulating hormone (rhTSH) recently was approved as an alternative to thyroid hormone withholding (THW) to elevate TSH for thyroid remnant ablation in differentiated thyroid carcinoma patients. High ablation success rates are reported with diverse rhTSH-aided 131I activities. Improved renal function causes ∼50% faster radioiodine clearance under euthyroidism versus hypothyroidism. Knowledge of comparative remnant radioiodine kinetics, particularly the remnant radiation dose in Gy/GBq of administered 131I activity (RDpA), could assist in choosing rhTSH-aided ablative activities.

Material and Methods: To compare the RDpA, determined through 124I-positron emission tomography/computed tomography (PET/CT), under the two stimulation methods, we retrospectively divided into two groups 55 consecutive totally-thyroidectomized, radioiodine-naïve patients. The rhTSH group (n=16) received 124I on thyroid hormone, 24 h after two consecutive daily intramuscular injections of rhTSH, 0.9 mg. The THW group (n=39) received 124I after weeks-long THW, when serum TSH first measured ≥25 mIU/L. We performed PET investigations 4 h, 24 h, 48 h, 72 h and 96 h and PET/CT 25 h after 124I administration.

Results: Median stimulated serum thyroglobulin was 15 times higher (p=0.023) and M1 disease almost twice as prevalent (p=0.05) in rhTSH versus THW patients. Mean±standard deviation RDpA was statistically equivalent between the groups: rhTSH, 461±600 Gy/GBq, THW, 302±329 Gy/GBq, two-sided p=0.258.

Conclusions: rhTSH or THW deliver statistically equivalent radiation doses to thyroid remnant and may be chosen based on safety, quality-of-life, convenience and pharmacoeconomic factors. Institutional fixed radioiodine activities formulated for use with THW need not be adjusted for rhTSH-aided ablation.



L. S. Freudenberg, MD, MA, MBA 

Department of Nuclear Medicine

University of Duisburg/Essen

Hufelandstraße 55

45122 Essen


Phone: +49/201/723 20 32

Fax: +49/201/723 59 64

Email: lutz.freudenberg@uni-due.de