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Incidence of radiation thyroiditis and thyroid remnant ablation success rates following 1110 MBq (30 mCi) and 3700 MBq (100 mCi) post‐surgical 131 I ablation therapy for differentiated thyroid carcinoma
Author(s) -
Cherk Martin H.,
Kalff Victor,
Yap Kenneth S. K.,
Bailey Michael,
Topliss Duncan,
Kelly Michael J.
Publication year - 2008
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.2008.03276.x
Subject(s) - medicine , thyroiditis , thyroid , subacute thyroiditis , thyroid cancer , thyroid carcinoma , ablation , incidence (geometry) , gastroenterology , radiation therapy , nuclear medicine , urology , endocrinology , physics , optics
Summary Objective To evaluate the relationships between thyroid remnant 131 I uptake, radiation thyroiditis and remnant ablation success rate between lower (1110 MBq) and higher (3700 MBq) initial ablative 131 I dose for post‐surgical ablation therapy for differentiated thyroid cancer. Design Patients having post‐surgical administration of 1110 MBq (68 patients) or 3700 MBq (115 patients) 131 I were retrospectively reviewed. Thyroid remnant 131 I uptake on a 48 h post‐administration scan was correlated with neck symptoms experienced. Patients were classified as having insignificant, mild or severe thyroiditis based on symptoms. Absent thyroid bed 131 I uptake on a follow‐up 74 MBq 131 I study was considered successful ablation. Results 183 patients were included. Median 131 I remnant uptake was 37 MBq. 21% (39/183) of patients developed thyroiditis. Incidence and severity of thyroiditis increased with increasing remnant 131 I activity ( P ≤ 0·0001). Risk of thyroiditis increased by 64% for every 37 MBq increase in remnant 131 I uptake. OR = 1·64 [1·36–1·99]. Severe thyoriditis was only seen with remnant 131 I uptake > 73 MBq. For patients treated with 1110 MBq and 3700 MBq, incidence of thyroiditis was 12% and 27% ( P = 0·02) and remnant ablation success rate was 76% and 84% ( P = NS), respectively. Occurrence of thyroiditis did not correlate with successful ablation. Conclusions Incidence and severity of radiation thyroiditis following 131 I remnant ablation therapy is directly related to thyroid remnant 131 I uptake. As 1110 MBq 131 I is associated with a significantly lower frequency of thyroiditis but similar remnant ablation rate to 3700 MBq, it warrants consideration for thyroid remnant ablation particularly in patients with low risk disease.