Factors Predicting Early Release of Thyroid Cancer Patients from the Isolation Room after Radioiodine-131 Treatment

  • Fatima, Nosheen (Department of Nuclear Medicine, Dr Ziauddin Hospital) ;
  • Zaman, Maseeh uz (Department of Radiology, Aga Khan University Hospital) ;
  • Zaman, Areeba (Dow Medical College, DUHS) ;
  • Zaman, Unaiza (Dow Medical College, DUHS) ;
  • Tahseen, Rabia (Dow Medical College, DUHS) ;
  • Shahid, Wajiha (Dow Medical College, DUHS)
  • Published : 2016.02.05


Background: Patients with differentiated thyroid cancers (DTC) who receive radioactive iodine-131 (RAI) are released from isolation when their dose rate is below the regulatory requirements. The purpose of this study was establish predicting factors for early release from the isolation facility after RAI administration in patients with DTC. Materials and Methods: This was a prospective study which included 96 (58 females and 38 males) patients with DTC who had received RAI from April 2013 till August 2015. The study was duly approved by the ethical committee of the institute. Patients who had complete information of primary tumor size (PTS), serum TSH, stimulated thyroglobulin level [sTg] with antibodies (IU/ml) at the time of RAI treatment were included. All had a normal serum creatinine level. To attain lower effective half-life good hydration and administration of soft laxative were ensured. Dose rate was measured (immediately, 24 h and 36 h) at 1 meter distance from anterior mid trunk and a dose rate <$50{\mu}Sv/h$ was considered as the releasing criterion. At 24 h 50 patients were released while the remaining 46 patients were released at 36 h. A post-ablative whole body scan (PA-WBIS) was performed 5-8 days after RAI ablation in all patients. Results: Patients released after 24 h were significantly younger, had smaller lesions with higher proportion of papillary cancer, lower sTg, lower sTg/TSH ratio and had received a lower dose of RAI as comapred to those who were discharged after 36 h. Serum TSH and gender were not found to have any significant correlation between two cohorts. ROC and multivariate analysis have shown age ${\leq}37years$, PTS ${\leq}3.8cm$, $RAI{\leq}150mCi$, $sTg{\leq}145ng/ml$ and $sTg/TSH{\leq}1.085$ as strong indepedent predictors for early release. Conclusions: We conclude that younger age (${\leq}37years$), smaller tumor size (${\leq}3.8cm$), lower RAI dose (${\leq}150mCi$), lower sTg (${\leq}145ng/ml$) and a lower sTg/TSH ratio (${\leq}1.085$) are significant independent predictors for release at 24 h after RAI treatment in DTC patients. Effective utilization of these factors could help the treating physicians to use limited number of internment facilities with higher throughput, lower cost and lower psychological stress to patients.


Radioactive iodine-131;differentiated thyroid cancer;isolation;early release;dose rate


  1. Barrington SF, Kettle AG, Doherty GM, et al (1996). Radiation dose rates from patients receiving iodine-131 therapy for carcinoma of the thyroid. Eur J Nucl Med, 23, 123-30.
  2. Borget I, Remy H, Chevalier J, et al (2008). Length and cost of hospital stay ofradioiodine ablation in thyroid cancer patients: comparison between preparationwith thyroid hormone withdrawal and thyrogen. Eur J Nucl Med Mol Imaging, 35, 1457-63.
  3. Chung JK (2002). Sodium iodide symporter: its role in nuclear medicine. J Nucl Med, 43, 1188-200.
  4. Cooper DS, Doherty GM, Haugen BRL, et al (2009). Revised American thyroid association management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid, 19, 1167-214.
  5. Higashi T, Nishii R, Yamada S, et al (2011). Delayed initial radioactive iodine therapy resulted in poor survival in patients with metastatic differentiated thyroid carcinoma: a retrospective statistical analysis of 198 cases. J Nucl Med, 52, 683-9.
  6. Jai HL, Seok GP (2010). Estimation of the Release Time from Isolation for Patients with differentiated thyroid cancer treated with high-dose I-131. Nucl Med Mol Imaging, 44, 241-5.
  7. Menzel C, Kranert WT, Dobert N, et al (2003). rhTSH stimulation before radioiodinetherapy in thyroid cancer reduces the effective half-life of 131I. J Nucl Med, 44, 1065-68.
  8. Machens A, HolzhausenHJ, Dralle H (2005). The prognostic value of primary tumor size in papillary and follicular thyroid carcinoma. Cancer, 103, 2269-73.
  9. Papadimitriou D, Sofia K, Loukia O, et al (2006). Differentiated thyroid cancer: comparison of therapeutic iodine-131biological elimination after discontinuation of levothyroxine versusadministration of recombinant human thyrotropin. AnnlNucl Med, 20, 63-7.
  10. Remy H, Borget I, Leboulleux S, et al (2008). 131I Effective half-life and dosimetry in thyroid cancer patients. J Nucl Med, 49, 1445-50.
  11. Schlumberger MJ (1998). Papillary and follicular thyroid carcinoma. New Engl J Med, 338, 297-306.
  12. Travis CC, Stabin MG (2006). 131I ablation treatment in young females after the Chernobyl accident. J Nucl Med, 47, 1723-27.
  13. Xhaard C, Ren Y, Clero E, et al (2014). Differentiated thyroid carcinoma risk factors in French Polynesia. Asian Pac J Cancer Prev, 15, 2675-80.
  14. Zaman M, Fatima N, Sajjad Z, Hashmi I (2012). High dose I-131 therapy on outpatient basis: imperative and no more a desire. PJNM, 2, 50-56
  15. Zaman M, Fatima N, Sajjad Z, et al (2012). Threshold primary tumour sizes for nodal and distant metastases in papillary and follicular thyroid cancers. Asian Pacific J Cancer Prev, 13, 2473-76.

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