title: Correlation of Consecutive Serum Thyroglobulin Levels During Hormone Withdrawal and Failure of Initial Radioiodine Ablation in Thyroid Cancer Patients.
abstract: OBJECTIVE
  The aim of this study was to evaluate the value of thyroglobulin (Tg) kinetics during preparation of radioiodine ablation for prediction of initial radioiodine ablation failure in thyroid cancer patients.
  
  
  METHODS
  Thyroid cancer patients after total thyroidectomy who underwent radioiodine ablation with 3-4 weeks of hormone withdrawal between May 2011 and January 2012 were included. Consecutive serum Tg levels 5-10 days before ablation (Tg1) and on the day of ablation (Tg2) were obtained. The difference between Tg1 and Tg2 (ΔTg), daily change rate of Tg (ΔTg/day) and Tg doubling time (Tg-DT) were calculated. Success of initial ablation was determined by the results of the follow-up ultrasonography, diagnostic radioiodine scan and stimulated Tg level after 6 to 20 months.
  
  
  RESULTS
  A total of 143 patients were included. Failed ablation was reported in 52 patients. Tg2 higher than 5.6 ng/ml and Tg-DT shorter than 4.2 days were significantly related to a high risk of ablation failure. ΔTg and ΔTg/day did not show significant correlation with ablation failure.
  
  
  CONCLUSIONS
  Thyroglobulin kinetics on consecutive blood sampling during hormone withdrawal may be helpful in predicting patients with higher risk of treatment failure of initial radioiodine ablation therapy in thyroid cancer patients.
authors.affiliation: Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, 137-701 Korea.
authors.forename: Hyukjin
authors.initials: H
authors.lastname: Yoon
authors.affiliation: Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, 137-701 Korea.
authors.forename: Sung Hoon
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, 137-701 Korea.
authors.forename: Joo Hyun
authors.initials: JH
authors.lastname: O
authors.affiliation: Department of Nuclear Medicine, College of Medicine, The Inje University Sanggye Paik Hospital, Seoul, Korea.
authors.forename: Ye Young
authors.initials: YY
authors.lastname: Seo
authors.affiliation: Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, 137-701 Korea.
authors.forename: Yeongjoo
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, 137-701 Korea.
authors.forename: Hyoungwoo
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Radiology, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Ryu
keywords: High-dose I-131 ablation therapy; Papillary thyroid carcinoma; Therapeutic failure; Thyroglobulin doubling time