Radioactive Iodine Ablation In Patients Research Articles

Outcomes of Patients with an Intermediate-Risk Group According to the Japanese Risk Classification of Papillary Thyroid Carcinoma

BackgroundThe management of intermediate-risk group of papillary thyroid cancer (PTC) is still vague, particularly regarding whether or not total thyroidectomy, postoperative radioactive iodine ablation (RAI-a), and postoperative TSH suppression are mandatory.MethodsThis retrospective study evaluated 680 PTC patients from 2010 to 2017, who were classified into the three risk groups as low, intermediate, and high-risk groups according to the criteria of the Japanese Association of Endocrine Surgeons (JAES) 2010 and underwent surgery according to the JAES guidelines. We retrospectively collected patient data for analyses of disease-free survivals in the intermediate-risk group patients.ResultsWe performed surgery on 680 PTC patients from 2010 to 2017. Of them, 297 were classified as the intermediate-risk group. DFS was not statistically significantly different in patients with/without total thyroidectomy and postoperative TSH suppression therapy. For RAI-a, DFS (95% confidence interval) at 3, 5, and 8 years were 93.2% (84.6 ~ 97.2), 81.6% (68,3 ~ 90.2), and 70.7% (51.4 ~ 84.6) in patients with postoperative RAI-a and 100%, 100%, and 100% in patients without postoperative RAI-a after total thyroidectomy, respectively. DFS of patients without RAI-a was superior to those with RAI-a (P < 0.0004). Multivariable analysis by stepwise selection method revealed that postoperative RAI-a was a risk factor with a hazard ratio of 5.69. (95% CI 1.998–16.21) (P = 0.001131).ConclusionsOur study did not show the efficacy of RAI-a in patients with intermediate-risk PTC. This study implies that judging the efficacy of adjuvant therapy such as RAI or TSh suppression in intermediate-risk patients is difficult.

Retrospective evaluation of radioactive iodine ablation therapy in the Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features (NIFTP) and Thyroid tumors with uncertain malignity potential

Background: Noninvasive Follicular Thyroid Neoplasm (NIFTP), Well differantiated thyroid tumor with uncertain malignity potential (WDT-UMP), follicular thyroid tumor with uncertain malignity potential (FT-UMP), and Hurtle cell neoplasia with uncertain malignity potential (HCN-UMP) have been included in the classification of thyroid tumors by WHO, with the incidence of thyroid cancer increasing every passing year. There is no consensus regarding the follow-up and treatment processes of these tumors. Our study aims to shed light on our clinical practice by evaluating the follow-up processes of the groups with and without radioactive iodine ablation in patients followed up with these diagnoses.&#x0D; Material and Methods: The 49 patients older than 18 years of age and followed for at least 12 months, who were performed subtotal and total thyroidectomy between 2015 and 2020 and were diagnosed with WDT- UMP, FT-UMP, HCN-UMP, and NIFTP according to histopathological examination were included to the study.&#x0D; Results: Tumor type rates did not differ between the groups that received and did not receive RAI treatment (p=0.361). The mean follow-up period did not differ between the groups that received and did not receive RAI treatment. Also the rates of RAI treatment according to tumor size did not differ (p=0.413). Tumor size was larger than 4 cm in 13 patients, and 1 patient from this group had received RAI treatment. Recurrence was not detected in the 49 patients included in our study who received or not receive RAI treatment. &#x0D; Conclusions: Some studies recommend giving RAI to these borderline thyroid tumors larger than 4 cm. But in our study no recurrence was detected in patients who did not receive RAI. That supports the view that patients could be followed without RAI treatment even if they are large tumors.

Unmeasurable stimulated thyroglobulin before radioactive iodine ablation predicts excellent long term outcome in patients with differentiated thyroid cancer

Abstract Aim To determine the likelihood of reaching unmeasurable stimulated thyroglobulin (sTG) levels after surgery for differentiated thyroid cancer (DTC). Methods Data on consecutive patients treated for DTC in a tertiary referral centre between May 2000 and June 2019 were retrospectively collected. Radioactive iodine ablation (RIA) was done after hormone withdrawal (before 2015) or after Thyrogen stimulation (more recent patients). During the study period, the biochemical assay for TG changed from a lower limit of detectability of 5 ng/dl to 0.2 ng/dl. Results A total of 403 patients (F=282; M=121) were included. sTG was &amp;lt;0.2 in 41 patients and during a median follow-up of 32 months, none had disease recurrence. sTG was 0.2–4.99 ng/dl in 104 patients and during a median follow-up of 27 months, 5 patients had evidence of either residual disease or local recurrence. sTG was reported as &amp;gt;5 in 258 patients and during a median follow-up of 63 months, 160 patients were disease free at the time of data collection. Patients who presented with locally advanced disease requiring modified radical neck dissection (n=78) had sTG higher than in those with earlier disease (n=325) (median 11.1 vs. 5.0ng/ml). There was a large difference in cervical uptake after RIA in patients with sTG 0.2–4.99 ng/dl (n=24) compared with those with sTG &amp;gt;20 ng/dl (n=32) (0.7% vs 1.54%). Conclusion Almost half of all patients with DTC achieved unmeasurable sTG after surgery. This could be due to earlier disease but can also serve as a quality control after thyroidectomy for thyroid cancer.

Immunomodulatory Effects of Omega-3 Fatty Acids in Patients with Differentiated Thyroid Cancer Before or After Radioiodine Ablation.

Thyroid cancer and radioactive iodine (RAI) ablation for postsurgical management may lead to uncontrolled inflammation. This study was intended to assess the prophylactic and therapeutic immunomodulatory effects of omega-3 fatty acids in patients with differentiated thyroid cancer (DTC). A total of 85 patients with DTC were allocated into two groups based on RAI dosage after thyroidectomy. Patients in each group were randomly distributed into three subgroups: G1 with RAI ablation only, G2 treated with omega-3 for 30 days before RAI ablation, and G3 treated with omega-3 for 30 days after RAI ablation. Fifteen healthy individuals were included as controls. Serum cytokine levels including IL-2, IL-4, IL-5, IL-6, IL-9, IL-10, IL-13, IL-17A, IL-17F, IL-21, IL-22, TNF-α and IFN-γ were determined by cytometric bead assay. IL-4, IL-6, IL-21 and IL-22 levels in patients with DTC were higher than in the healthy controls. Regardless of RAI dosage, IL-6 showed an increasing trend after RAI ablation. IL-4, IL-22, and IL-17A remained at considerably higher levels than in the healthy controls after RAI ablation. Within-group comparisons showed a significant reduction in Th1+Th17/Th2+Th22 ratio in G2 patients 1 week after RAI ablation. Between-group comparisons showed increased IL-10 levels in G3 compared with G1 patients one week after high-dose RAI ablation. In G3, Th1+Th17/Th2+Th22 and Th1+Th17/Th2+Th9+Th22 ratios were remarkably lesser than in G2 patients 1 month after intermediate-dose RAI ablation. Our results showed better anti-inflammatory effects of omega-3 when it was used therapeutically after RAI ablation in patients with DTC than when it was used prophylactically before RAI.

Long-Term Oncological Outcome Comparison between Intermediate- and High-Dose Radioactive Iodine Ablation in Patients with Differentiated Thyroid Carcinoma: A Propensity Score Matching Study.

Background Radioactive iodine (RAI) ablation is recommended for most patients with differentiated thyroid carcinoma (DTC) after total thyroidectomy (TT). We aimed to compare long-term outcomes between intermediate-dose (100 mCi) and high-dose (150 mCi) RAI ablation therapy in patients with DTC using propensity score matching analysis. Methods This was a retrospective study of 1448 patients with DTC who underwent RAI ablation after TT. Propensity score matching was performed using the extent of operation, tumor size, extrathyroidal extension, multifocality, lymphatic invasion, vascular invasion, perineural invasion, number of positive lymph nodes (LNs), ATA risk stratification system, T stage, N stage, TNM stage, preoperative serum Tg and TgAb levels, and post-RAI serum Tg and TgAb levels. Results Recurrence rates in the intermediate- and high-dose groups were 3.1% and 5.6%, respectively. After propensity score matching, LN ratio >0.22 (HR, 2.915; 95% CI, 1.228–6.918; p=0.015) and serum Tg >10 ng/mL after RAI (HR, 3.976; 95% CI, 1.839–8.595; p < 0.001) were significant predictors of recurrence. Kaplan–Meier analysis showed no significant difference in DFS before or after propensity score matching (p=0.074 and p=0.378, respectively). Conclusions Intermediate-dose RAI ablation for the adjuvant treatment of DTC is sufficient as compared to high-dose RAI ablation. Further prospective or multicenter studies should be conducted to clarify the prognosis of intermediate-dose RAI ablation.

Longer-term recurrence rate after low versus high dose radioiodine ablation for differentiated thyroid Cancer in low and intermediate risk patients: a meta-analysis

BackgroundRegarding the longer-term recurrence rate the optimal activity for the remnant thyroid ablation in patients with differentiated thyroid cancer (DTC) is discussed controversially. For the short-term ablation success rate up to 12 months there are already several meta-analyses. In this study we performed the first meta-analysis regarding the longer-term recurrence rate after radioactive 131-I administration.MethodsWe conducted an electronic search using PubMed/MEDLINE, EMBASE and the Cochrane Library. All randomized controlled trials (RCTs) assessed the recurrence rate after radioactive iodine ablation in patients with DTC, with a follow-up of at least two years were selected. Statistics were performed by using Review Manager version 5.3 and Stata software.ResultsFour RCTs were included in the study, involving 1501 patients. There was no indication for heterogeneity (I2 = 0%) and publication bias. The recurrence rate among patients who had a low dose 131-iodine ablation was not higher than for a high dose activity (odds ratio (OR) 0.93 [95% confidence interval (CI) 0.53–1.63]; P = 0.79). The mean follow-up time was between 4.25 and 10 years. The subgroup analysis regarding the TSH stimulated thyroglobulin values (< 10 ng/mL versus < 2 ng/mL versus ≤1 ng/mL) showed no influence on recurrence rate.ConclusionsFor the first time we showed that the longer-term, at least 2-year follow-up, recurrence rate among patients who had 131-iodine ablation with 1.1 GBq was not higher than with 3.7 GBq.

Is it Better to Defer the Radioactive Iodine Ablation in Patients with Differentiated Thyroid Cancer in the Current COVID 19 Pandemic?

Is it Better to Defer the Radioactive Iodine Ablation in Patients with Differentiated Thyroid Cancer in the Current COVID 19 Pandemic?

The role of radioactive iodine therapy in papillary thyroid cancer: an observational study based on SEER.

BackgroundPapillary thyroid cancer (PTC) is a common endocrine malignancy with relatively good prognosis. Radioactive iodine (RAI) is considered effective for patients with total or nearly total thyroidectomy, but the beneficial effects of RAI are still controversial.Materials and methodsTo determine whether RAI therapy could improve the survival rates of PTC patients, we conducted a retrospective analysis using data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) program. Disease-specific survival (DSS) was obtained using multivariate Cox proportional hazard regressions.ResultsDSS was improved by RAI ablation in patients with tumor >2 cm, age >45 years and gross extrathyroidal or lymph node metastasis. In a further analysis, RAI therapy did not improve the DSS in patients with tumor <2 cm except those with distant metastasis. For patients with tumor >2 cm, those involving gross extrathyroidal extension, age >45 years or disease in the lymph nodes, DSS was improved after RAI therapy. Patients with distant metastasis always benefited from RAI ablation.ConclusionRAI ablation should be recommended to patients with tumor <2 cm and distant metastasis or patients with tumor >2 cm and one of the following risk factors: gross extrathyroidal extension, age >45 years, lymph node and distant metastases.

Computed tomography features of the major salivary glands after radioactive iodine ablation in patients with papillary thyroid carcinoma.

No previous study has investigated computed tomography (CT) features of the major salivary glands (MSGs) after postoperative radioactive iodine ablation (RIA). This study aimed to assess CT features of the MSGs after RIA in patients with papillary thyroid carcinoma (PTC). The study population comprised consecutively registered PTC patients who had undergone total thyroidectomy, RIA, follow-up neck ultrasonography (US), and neck CT. The US and CT features of the parotid and submandibular glands in each patient were retrospectively evaluated by a single radiologist. Post-RIA changes were determined by comparisons between follow-up neck US results (main reference) and between preoperative and post-RIA neck CT features. Of the 28 patients, 13 (46.4%) showed post-RIA changes in the parotid glands (n=8), submandibular glands (n=0), or both (n=5) on neck CT. Of the 56 MSGs in 28 patients, post-RIA changes were more common in the parotid glands (n=23, 41.1%) than in the submandibular glands (n=8, 14.3%). The common CT findings of post-RIA changes in the parotid gland included low parenchymal attenuation, decreased glandular size, a lobulated margin, decreased or increased parenchymal enhancement, and an inhomogeneous enhancement pattern, whereas common CT findings of post-RIA changes in the submandibular gland included decreased glandular size, a lobulated margin, iso-enhancement, and an inhomogeneous enhancement pattern. The common CT features of post-RIA changes in MSGs include decreased glandular size, a lobulated margin, and an inhomogeneous enhancement pattern.

Impact of age and sex on the quality of life following radioactive iodine ablation in patients with thyroid cancer.

We assessed patient discomfort and identified factors predictive of discomfort while receiving radioactive iodine (RAI) ablation. Between August 2015 and April 2016, 52 patients with differentiated thyroid cancer were enrolled in this study. All patients received recombinant human thyroid stimulating hormone (rhTSH) aided RAI ablation using 3.7 GBq or 5.55 GBq of RAI. Discomfort during their stay for RAI ablation was evaluated using a symptom questionnaire. We analyzed the relationship between the patient's clinical data and the scores for the 15 items of the symptom questionnaire. We compared scores of questionnaires between male and female, under 45 years old and 45 and older, RAI activity of 3.7 GBq and 5.55 GBq. Also, scores of daily questionnaires were tested for differences. Most patients did not have severe discomfort, but some patients had mild discomfort during their stay for RAI ablation, despite using rhTSH. Important determinants of discomfort were sex and age. Female patients reported more symptoms of fatigue, facial edema, cold intolerance, and nausea. Older patients (45 and older) complained of insomnia more often. However, the dose of RAI ablation (3.7 GBq vs 5.55 GBq) did not affect the scores of questionnaires. Sex and age were important predictors of patient's discomfort during RAI ablation. Clinicians need to explain more about treatment and predicted discomforts to such patients before RAI ablation.

Association of Xerostomia and Ultrasonographic Features of the Major Salivary Glands After Radioactive Iodine Ablation for Papillary Thyroid Carcinoma.

The objective of this study is to evaluate the association between xerostomia and sonographic features of the major salivary glands after patients undergo radioactive iodine ablation (RIA) for papillary thyroid carcinoma (PTC). The study included 256 consecutive patients who underwent total thyroidectomy, RIA, and neck ultrasound examinations. Changes in the ultrasound features of the parotid and submandibular glands after RIA were evaluated retrospectively by a single radiologist, on the basis of direct comparison of sonograms obtained before and after RIA. Clinical data, including the presence of xerostomia, were investigated retrospectively by the same radiologist via a review of the electronic medical records. For 111 of the 256 patients (43.4%), ultrasound examination revealed changes in the major salivary glands after RIA. The presence of xerostomia was undetermined in 85 of the 256 patients. Among the remaining 171 patients, the frequency of xerostomia was 36.8% (63/171). When patients with xerostomia were compared with those without xerostomia, no statistically significant differences in patient sex and age, the dose of RIA received, or the number of RIA sessions were noted (p > 0.05). Considering the changes in the ultrasound features of the major salivary glands after RIA, no statistically significant association was found between xerostomia and the number of involved major salivary glands or the presence of an involved submandibular gland (p > 0.05). In this study, ultrasound was unhelpful for evaluating xerostomia after RIA in patients with PTC.

Efficacy of Low-dose and High-dose Radioactive Iodine Ablation With rhTSH in Korean Patients With Differentiated Thyroid Carcinoma: The First Report in Nonwestern Countries.

The aim of this study was to confirm the equivalent efficacy of recombinant human TSH (rhTSH) and thyroid hormone withdrawal (THW) as used in the preparation for low-dose and high-dose radioactive iodine (RAI) ablation in Korean patients with differentiated thyroid carcinoma. This retrospective study was designed to compare the efficacy of rhTSH and THW when used before ablation with low-dose (30 mCi) and high-dose (100 mCi) RAI, respectively. The study group included 570 patients with DTC with tumors staged T1 to T3, N0 to N1, and M0. Before RAI ablation, 190 patients used rhTSH and 380 patients matched by age, sex, T-stage, and N-stage used THW. The success of ablation was evaluated in each group based on 4 criteria: (1) stimulated thyroglobulin (sTg) <2 ng/mL, (2) sTg<2 ng/mL and negative diagnostic whole-body scan (DxWBS), (3) sTg<1 ng/mL, and (4) sTg<1 ng/mL and negative DxWBS. When both sTg<2 ng/mL and negative DxWBS were selected as criteria for success in patients treated with low-dose RAI, the success rates were 80.5% and 77.0% with rhTSH and THW, respectively (95% confidence interval, 5.9-12.8). Using both sTg<1 ng/mL and negative DxWBS as criteria, success rates were 78.2% and 71.8% with rhTSH and THW, respectively (95% confidence interval, 3.6-16.2). Using any criteria for success, low-dose RAI ablation with rhTSH was as effective as THW. Similar results were found for high-dose RAI ablation in patients using either rhTSH or THW. Low-dose and high-dose RAI ablation were equally effective using either rhTSH or THW before ablation in Korean patients with DTC, respectively.

Regional Variation across Canadian Centers in Radioiodine Administration for Thyroid Remnant Ablation in Well-Differentiated Thyroid Cancer Diagnosed in 2000-2010.

Background. Use of radioactive iodine (RAI) ablation has been reported to vary significantly between studies. We explored variation in RAI ablation care patterns between seven thyroid cancer treatment centers in Canada. Methods. The Canadian Collaborative Network for Cancer of the Thyroid (CANNECT) is a collaborative registry to describe and analyze patterns of care for thyroid cancer. We analyzed data from seven participating centers on RAI ablation in patients diagnosed with well-differentiated (papillary and follicular) thyroid cancer between 2000 and 2010. We compared RAI ablation protocols including indications (based on TNM staging), preparation protocols, and administered dose. We excluded patients with known distant metastases at time of RAI ablation. Results. We included 3072 patients. There were no significant differences in TNM stage over time. RAI use increased in earlier years and then declined. The fraction of patients receiving RAI varied significantly between centers, ranging between 20–85% for T1, 44–100% for T2, 58–100% for T3, and 59–100% for T4. There were significant differences in the RAI doses between centers. Finally, there was major variation in the use of thyroid hormone withdrawal or rhTSH for preparation of RAI ablation. Conclusion. Our study identified significant variation in use of RAI for ablation in patients with well-differentiated thyroid cancer both between Canadian centers and over time.

Ultrasonographic Features of the Major Salivary Glands after Radioactive Iodine Ablation in Patients with Papillary Thyroid Carcinoma

The aim of this study was to evaluate the ultrasonographic features of the major salivary glands (MSGs) after post-operative radioactive iodine ablation (RIA) in patients with papillary thyroid carcinoma (PTC). The study population comprised 202 consecutively registered PTC patients who had undergone total thyroidectomy, RIA and follow-up neck ultrasonography. The ultrasonographic features of the MSGs in each patient were retrospectively evaluated by a single radiologist, and the presence of post-RIA changes was determined by direct comparisons of pre- and post-RIA follow-up ultrasonographic scans. Of the 202 patients, 94 (46.5%) had post-RIA changes in the MSGs on follow-up ultrasonography. RIA dose was closely associated with the prevalence of post-RIA changes. Post-RIA changes were more common in the parotid glands (n = 93, 46.0%) than in the submandibular glands (n = 7, 3.5%). Common ultrasonographic findings representing post-RIA changes in MSGs included coarse echotexture, decreased echogenicity, lobulated margin and decreased gland size.

Reprint of: Stimulated thyroglobulin levels after thyroidectomy could guide the need for radioactive iodine ablation in patients with well differentiated thyroid cancer

Background: The routine use of radioactive iodine ablation (RIA) in all patients with papillary/follicular thyroid cancer >10 mm is increasingly controversial. The hypothesis explored in this study is that radical thyroid surgery can lead to unmeasurable stimulated thyroglobulin (sTG) levels in a significant proportion of patients who could therefore avoid RIA. Stimulated thyroglobulin levels after thyroidectomy could guide the need for radioactive iodine ablation in patients with well differentiated thyroid cancerEuropean Journal of Surgical OncologyVol. 40PreviewBackground: The routine use of radioactive iodine ablation (RIA) in all patients with papillary/follicular thyroid cancer >10 mm is increasingly controversial. The hypothesis explored in this study is that radical thyroid surgery can lead to unmeasurable stimulated thyroglobulin (sTG) levels in a significant proportion of patients who could therefore avoid RIA. Full-Text PDF

Stimulated thyroglobulin levels after thyroidectomy could guide the need for radioactive iodine ablation in patients with well differentiated thyroid cancer

Background: The routine use of radioactive iodine ablation (RIA) in all patients with papillary/follicular thyroid cancer >10 mm is increasingly controversial. The hypothesis explored in this study is that radical thyroid surgery can lead to unmeasurable stimulated thyroglobulin (sTG) levels in a significant proportion of patients who could therefore avoid RIA.

Salivary Gland Function 5 Years After Radioactive Iodine Ablation in Patients with Differentiated Thyroid Cancer: Direct Comparison of Pre- and Postablation Scintigraphies and Their Relation to Xerostomia Symptoms

Chronic sialadenitis is one of the most frequent chronic complications after radioactive iodine (RAI) therapy for thyroid cancer. To evaluate the long-term effects of RAI ablation on salivary gland function, we investigated scintigraphic changes in salivary glands by direct comparison of two salivary gland scintigraphies (SGSs) taken before and at 5 years after an RAI ablation. SGS was performed just before RAI ablation (pre-SGS) and ∼5 years after RAI ablation (F/U SGS) in 213 subjects who underwent thyroidectomy for thyroid cancer. The uptake score (U score) was graded, and the ejection fraction (EF) was quantified for the parotid and submandibular glands at pre-SGS and F/U SGS. Changes in salivary gland function were graded as mild, moderate, or severe according to the differences in U score and EF between the two SGSs. Xerostomia was assessed and compared with the SGS findings. Worsening of the U score was observed in 182 of 852 salivary glands (total: 21.3%; mild: 4.2%, moderate: 7.4%, severe: 9.7%), and 47.4% of the patients had a worsening U score for at least one of four salivary glands. A decrease in EF was observed in 173 of 852 salivary glands (total: 20.3%; mild: 5.4%, moderate: 6.8%, severe: 8.1%), and 43.7% of the patients experienced a decrease in the EF of at least one of the four salivary glands. Bilateral parotid gland dysfunction was the most commonly observed condition. Thirty-five (16.4%) patients complained of xerostomia at 5 years after RAI ablation. Scintigraphic changes in salivary gland function and xerostomia were more common in patients receiving 5.55 GBq, compared with 3.7 GBq. Xerostomia was more common in patients with submandibular gland dysfunction than those with parotid gland dysfunction (68.8% vs. 33.3%, p<0.05). The number of dysfunctional salivary glands was correlated with xerostomia (p<0.01). About 20% of the salivary glands were dysfunctional on SGS 5 years after a single RAI ablation, especially in patients who received higher doses of RAI. While parotid glands are more susceptible to (131)I-related damage, xerostomia was more associated with submandibular gland dysfunction and the prevalence of dysfunctional salivary glands.

Recombinant Human Thyroid-Stimulating Hormone To Stimulate 131-1 Uptake For Remnant Ablation And Adjuvant Therapy

To review the current literature with regard to the use of recombinant human thyroid stimulating hormone (rhTSH) as an adjunct to radioactive iodine (RAI) remnant ablation and adjuvant therapy. Literature review of clinical studies examining rhTSH and/or thyroid hormone withdrawal preparations for RAI remnant ablation. The primary endpoints evaluated were (1) effectiveness at ablating the thyroid bed as demonstrated by the lack of significant uptake in the thyroid bed on follow-up diagnostic imaging and (2) effectiveness in facilitating the adjuvant therapy function of RAI ablation as manifested by follow-up thyroid stimulating hormone (TSH)-stimulated serum thyroglobulin levels and clinical outcomes (recurrence rates, likelihood of having no evidence of disease at final follow-up). RAI remnant ablation can be successfully achieved using either traditional thyroid hormone withdrawal or recombinant human TSH preparation. While initial studies included primarily thyroid cancer patients at low risk of recurrence, more recent studies suggest that rhTSH can also be effectively used as preparation for RAI ablation in patients with an intermediate or high risk of recurrence. Furthermore, while early studies focused primarily on the endpoint of thyroid bed remnant ablation, more recent retrospective studies suggest that final clinical outcomes (recurrence rates, likelihood of achieving no evidence of disease status at final follow-up) over 5-10 years of follow-up are very similar with either method of preparation. rhTSH is an effective alternative to thyroid hormone withdrawal in preparation for RAI remnant ablation in patients without evidence of distant metastases who are at low, intermediate, or high risk of recurrence.