Effect of administrated activity, admission number and TSH level on radiation retention curve of patients taking iodine-131 therapy for differentiated thyroid carcinoma: Looking beyond established regulations

Document Type : Original Article


1 Department of Nuclear Medicine, Seyedoshohada Hospital, Isfahan University of Medical Sciences, Isfahan, Iran

2 The Persian Gulf Nuclear Medicine Research Center, Bushehr University of Medical Sciences, Bushehr, Iran

3 Department of Biostatistics, School of Public Health, Bushehr University of Medical Sciences, Bushehr, Iran

4 Department of Health Promotion, The Persian Gulf Tropical Medicine Research Center, Bushehr University of Medical Sciences, Bushehr, Iran


Introduction: Retention of I-131 in the body of patients with differentiated thyroid carcinoma (DTC) has a direct effect on therapeutic outcome of radioiodine therapy. There are several factors that may influence retention time of radioiodine in the body of these patients. In this study we are going to assess effects of administered radioiodine activity, serum thyroid stimulating hormone (TSH) level and also admission/administration number on the retention of I-131 in the body of DTC patients.
Methods: Number of 92 DTC patients, with different TSH levels ranged from 32 mIU/ml to 250 mIU/ml, was treated with different I-131 activities ranged from 1850 MBq to 7400 MBq. They received one, two or three sessions of radioiodine therapy based on severity of cancer. Post-therapy dosimetry for all the patients was performed immediately, 6 hours, 12 hours, 24 hours and one week after the administration of  activity to calculate clearance rate of the I-131.
Results:Basedon our observations,there wasa direct correlation between administered radioiodine activities to the patients and clearance rate of the activity from their bodies. Also, those patients who had been admitted for the third time to receive their third radioiodine administration had higher clearance rate as compared to those who had their first or second admissions. TSH level above 32 mIU/ml did not show any effect on clearance rate of I-131.

Conclusion: Based on our findings, clearance rate of I-131 is affected by amount of administered radioiodine activities to the patients and number of radioiodine therapy sessions, but serum TSH level above 32 mIU/ml had no effect on this quantity.


Main Subjects

  1. Burns WR, Zeiger MA. Differentiated thyroid cancer. Semin Oncol. 2010 Dec;37(6):557-66.
  2. Sampson E, Brierley JD, Le LW, Rotstein L, Tsang RW. Clinical management and outcome of papillary and follicular (differentiated) thyroid cancer presenting with distant metastasis at diagnosis. Cancer. 2007 Oct 1;110(7):1451-6.
  3. Vaisman F, Corbo R, Vaisman M. Thyroid carcinoma in children and adolescents-systematic review of the literature. J Thyroid Res. 2011;2011:845362.
  4. Vrachimis A, Riemann B, Gerss J, Maier T, Schober O. Peace of mind for patients with differentiated thyroid cancer? Nuklearmedizin. 2013;52(4):115-20.
  5. Taylor A, Schuster DM, Alazraki N. A clinicians' guide to nuclear medicine. 2nd ed: Society of Nuclear Medicine; 2000. p. 423.
  6. Kwong N, Marqusee E, Gordon MS, Larsen PR, Garber JR, Kim MI, Alexander EK. Long-term, treatment-free survival in select patients with distant metastatic papillary thyroid cancer. Endocr Connect. 2014 Dec;3(4):207-14.
  7. Pak K, Cheon GJ, Kang KW, Kim SJ, Kim IJ, Kim EE, Lee DS, Chung JK. The effectiveness of recombinant human thyroid-stimulating hormone versus thyroid hormone withdrawal prior to radioiodine remnant ablation in thyroid cancer: a meta-analysis of randomized controlled trials. J Korean Med Sci. 2014 Jun;29(6):811-7.
  8. Baranauskas Z, Valuckas KP, Tiskevicius S. Outcomes of long-term combined treatment in follicular thyroid carcinoma. Medicina (Kaunas). 2010;46(4):268-74.
  9. Mazzaferri EL, Kloos RT. Clinical review 128: Current approaches to primary therapy for papillary and follicular thyroid cancer. J Clin Endocrinol Metab. 2001 Apr;86(4):1447-63.
  10. Carballo M, Quiros RM. To Treat or Not to Treat: To treat or not to treat: the role of adjuvant radioiodine therapy in thyroid cancer patients. J Oncol. 2012;2012:707156.
  11. Handkiewicz-Junak D, Wloch J, Roskosz J, Krajewska J, Kropinska A, Pomorski L, Kukulska A, Prokurat A, Wygoda Z, Jarzab B. Total thyroidectomy and adjuvant radioiodine treatment independently decrease locoregional recurrence risk in childhood and adolescent differentiated thyroid cancer. J Nucl Med. 2007 Jun;48(6):879-88.
  12. Tuttle RM, Leboeuf R, Robbins RJ, Qualey R, Pentlow K, Larson SM, Chan CY. Empiric radioactive iodine dosing regimens frequently exceed maximum tolerated activity levels in elderly patients with thyroid cancer. J Nucl Med. 2006 Oct;47(10):1587-91.
  13. Verburg FA, Lassmann M, Mäder U, Luster M, Reiners C, Hänscheid H. The absorbed dose to the blood is a better predictor of ablation success than the administered 131I activity in thyroid cancer patients. Eur J Nucl Med Mol Imaging. 2011 Apr;38(4):673-80.
  14. Papadimitriou D, Kottou S, Oros L, Ilias I, Molfetas M, Tsapaki V, Perris A, Christakopoulou I. Differentiated thyroid cancer: comparison of therapeutic iodine 131 biological elimination after discontinuation of levothyroxine versus administration of recombinant human thyrotropin. Ann Nucl Med. 2006 Jan;20(1):63-7.
  15. Luster M, Clarke SE, Dietlein M, Lassmann M, Lind P, Oyen WJ, Tennvall J, Bombardieri E; European Association of Nuclear Medicine (EANM). Guidelines for radioiodine therapy of differentiated thyroid cancer. Eur J Nucl Med Mol Imaging. 2008 Oct;35(10):1941-59.
  16. Duntas L, Grab-Duntas BM. Risk and prognostic factors for differentiated thyroid cancer. Hell J Nucl Med. 2006 Sep-Dec;9(3):156-62.
  17. Podoba J. Recombinant human thyrotropin in follow-up of patients with differentiated thyroid cancer. Bratisl Lek Listy. 2010;111(1):38-40.
  18. Rivkees SA, Mazzaferri EL, Verburg FA, Reiners C, Luster M, Breuer CK, Dinauer CA, Udelsman R. The treatment of differentiated thyroid cancer in children: emphasis on surgical approach and radioactive iodine therapy. Endocr Rev. 2011 Dec;32(6):798-826.
  19. Fallahi B, Beiki D, Takavar A, Fard-Esfahani A, Gilani KA, Saghari M, Eftekhari M. Low versus high radioiodine dose in postoperative ablation of residual thyroid tissue in patients with differentiated thyroid carcinoma: a large randomized clinical trial. Nucl Med Commun. 2012 Mar;33(3):275-82.
  20. Sabra MM, Grewal RK, Ghossein RA, Tuttle RM. Higher administered activities of radioactive iodine are associated with less structural persistent response in older, but not younger, papillary thyroid cancer patients with lateral neck lymph node metastases. Thyroid. 2014 Jul;24(7):1088-95.
  21. Mäenpää HO, Heikkonen J, Vaalavirta L, Tenhunen M, Joensuu H. Low vs. high radioiodine activity to ablate the thyroid after thyroidectomy for cancer: a randomized study. PLoS One. 2008 Apr 2;3(4):e1885.
  22. Ravichandran R, Binukumar J, Saadi AA. Estimation of effective half life of clearance of radioactive Iodine (I) in patients treated for hyperthyroidism and carcinoma thyroid. Indian J Nucl Med. 2010 Apr;25(2):49-52.
  23. North DL, Shearer DR, Hennessey JV, Donovan GL. Effective half-life of 131I in thyroid cancer patients. Health Phys. 2001 Sep;81(3):325-9.
  24. Venencia CD, Germanier AG, Bustos SR, Giovannini AA, Wyse EP. Hospital discharge of patients with thyroid carcinoma treated with 131I. J Nucl Med. 2002 Jan;43(1):61-5.
  25.  Azizmohammadi Z, Tabei F, Shafiei B, Babaei AA, Jukandan SM, Naghshine R, Javadi H, Nabipour I, Assadi M, Asli IN. A study of the time of hospital discharge of differentiated thyroid cancer patients after receiving iodine-131 for thyroid remnant ablation treatment. Hell J Nucl Med. 2013 May-Aug;16(2):103-6.
  26. Tabei F, Neshandar Asli I, Azizmohammadi Z, Javadi H, Assadi M. Assessment of radioiodine clearance in patients with differentiated thyroid cancer. Radiat Prot Dosimetry. 2012 Dec;152(4):323-7.
  27. Ejeh JE, Adedapo KS. Relationship between TSH level and effective half-life of I-131 in differentiated thyroid cancer patients. J Cell Sci Ther. 2011; S2:006.
  28. Schneider DF, Chen H. New developments in the diagnosis and treatment of thyroid cancer. CA Cancer J Clin. 2013 Nov-Dec;63(6):374-94.
  29. Neshandar Asli I, Siahkali AS, Shafie B, Javadi H, Assadi M. Prognostic value of basal serum thyroglobulin levels, but not basal antithyroglobulin antibody (TgAb) levels, in patients with differentiated thyroid cancer. Mol Imaging Radionucl Ther. 2014 Jun;23(2):54-9.