Citations

Abstract Disclosure: S.L. Samson: Consulting Fee; Self; Novartis Pharmaceuticals, Chiasma. M. Bolanowski: Grant Recipient; Self; Amryt, Recordati, Pfizer, Inc., Novartis Pharmaceuticals, Ipsen, IBSA, Teva Pharmaceutical Industries Ltd., Berlin Chemie. Speaker; Self; Amryt, Recordati, Pfizer, Inc., Novartis Pharmaceuticals, Ipsen, IBSA, Teva Pharmaceutical Industries Ltd., Berlin Chemie. S. Zhang: None. Y. Yu: None. P. Witek: Grant Recipient; Self; Novartis Pharmaceuticals, Ipsen, Recordati, Novo Nordisk, Xeris Pharmaceuticals (Strongbridge), Lilly USA, LLC. Speaker; Self; Novartis Pharmaceuticals, Ipsen, Recordati, Novo Nordisk, Xeris Pharmaceuticals (Strongbridge), Lilly USA, LLC. N. Kietsiriroje: None. A. Piacentini: Employee; Self; Recordati. A.M. Pedroncelli: Employee; Self; Recordati. U. Feldt-Rasmussen: Advisory Board Member; Self; Novartis Pharmaceuticals, Recordati, Novo Nordisk, Xeris Pharmaceuticals (Strongbridge). Grant Recipient; Self; Ipsen, Recordati, Novo Nordisk. Speaker; Self; Ipsen, Recordati, Novo Nordisk. Introduction: Pasireotide efficacy and safety in persons with acromegaly or Cushing’s disease (CD) is confirmed in a comprehensive clinical trial program. Pasireotide-induced hyperglycemia events, expected based on the drug’s mechanism of action, are manageable with low rates of treatment discontinuation. To advance knowledge on pasireotide-induced hyperglycemia management, a prospective randomized Phase IV study (B2219, NCT02060383) was conducted. This secondary analysis assessed factors that might predict development of pasireotide-induced hyperglycemia. Methods: In B2219, participants (Pts) with acromegaly or CD who did not need therapy for hyperglycemia or were managed with metformin alone entered the non-randomized observational arm. Pts who developed hyperglycemia not managed with metformin alone were randomized to incretin-based therapy or insulin. This analysis evaluated Pts according to whether therapy for hyperglycemia during pasireotide treatment was needed. Logistic regression analyses evaluated quantitative and qualitative predictive factors associated with pasireotide-induced hyperglycemia. Results: Of 190 Pts with acromegaly and 59 with CD, 88 and 15, respectively, did not need antihyperglycemic medication during pasireotide treatment; Pt characteristics were generally balanced across subgroups at study baseline (BL). Most Pts who did not develop hyperglycemia had a mean age of <40 years (acromegaly 62.5%, CD 86.7%), BL glycated hemoglobin (HbA1c) <6.5% (acromegaly 98.9%, CD 100.0%) and BL fasting plasma glucose (FPG) <100 mg/dL (acromegaly 76.1%, CD 100.0%). Age (odds ratio [OR] 1.0, 95% CI 1.0−1.1), BL HbA1c (OR 3.5, 95% CI 1.3−9.9) and prediabetes or diabetes conditions (OR 3.0, 95% CI 1.2−7.6) were identified as risk factors associated with pasireotide-induced hyperglycemia in Pts with acromegaly. BL FPG (OR 1.2, 95% CI 1.0−1.3) was associated with increased risk of pasireotide-induced hyperglycemia in Pts with CD. Overall, adverse events (AEs) of hyperglycemia and diabetes mellitus (investigator reported) occurred in 21.1% and 14.2% of Pts with acromegaly and 28.8% and 11.9% of Pts with CD, respectively. More Pts who had diabetes or prediabetes conditions at BL had hyperglycemia-related AEs than Pts with normal glucose levels. Hyperglycemia-related AEs were managed with antihyperglycemic medication (acromegaly 26.3%, CD 30.5%); few Pts temporarily interrupted treatment (acromegaly 3.7%, CD 10.2%). Conclusions: These data suggest that age, HbA1c, FPG and having prediabetes or diabetes conditions at BL are associated with increased risk of developing pasireotide-induced hyperglycemia. AEs were manageable with antihyperglycemic medication. Potential risk factors associated with pasireotide-induced hyperglycemia may be used to identify Pts who need vigilant monitoring to ensure optimal outcomes during pasireotide treatment. Presentation: Thursday, June 15, 2023

Abstract Disclosure: P.L. castellanos: None. S.E. Meek: None. A.M. Chindris: None. V.J. Bernet: None. Approximately 250 cases of papillary thyroid cancer (PTC) within a thyroglossal duct cyst (TGDC) have been reported worldwide. The presence of PTC within a TGDC is rare representing less than 1 % of all TGDC cases. This report describes the case of a young male with PTC in a TGDC suspicious nodules. We present this case along with a review of the literature related to this very uncommon finding. Papillary thyroid carcinoma is a very rare disease but always should be considered when speaking of a mass at the level of the central neck. There is a considerable controversy regarding the role of thyroidectomy to treat thyroglossal duct cyst carcinoma since the treatment of choice is Sistrunk procedure and the only indications to make a thyroidectomy will be aggressive disease and more than 45 years old according to some articles but without any consensus now. With a cure rate of 95 % and recurrence rate of 3 -10 % when this cancer is treated by Sistrunk operation, it doesn’t seem necessary to do an extent surgery if there is not enough thyroid compromised. Long term follow up is necessary to exclude the development of thyroid cancer. Presentation Date: Saturday, June 17, 2023

Abstract Disclosure: D. Toro-Tobon: None. J.C. Morris: None. C. Hilger: None. C.S. Peskey: None. D.M. Jolanta: None. M.M. Ryder: None. Objective: Patients with metastatic differentiated thyroid cancer (DTC) that are radioactive iodine (RAI) refractory (RAIR) have a poor prognosis. Redifferentiation therapy (RDT) has emerged as a potential approach to restore RAI avidity in this disease. The aim of this study was to examine the efficacy and predictors of RAI restoration in RAIR disease, as well as examine the outcomes of patients re-treated with high dose RAI following RDT. Methods: A retrospective review was conducted of 33 patients with RECIST-progressive metastatic RAIR-DTC who underwent RDT between 2017 and 2022 at the Mayo Clinic. All patients underwent genomic profiling, and either MEK inhibitor alone or combination BRAF-MEK inhibitors were prescribed for 4 weeks. At week 3, Thyrogen-stimulated I-123 whole body scans were performed. Those with increased RAI avidity in metastatic foci received high dose I-131 therapy using a previously published modified dosimetry protocol. Baseline and clinicopathologic outcomes were comprehensively reviewed. Results: Of the 33 patients, 12 of 23 (52%) with papillary thyroid cancers (PTC), 4 of 4 (100%) with follicular variant PTCs (FV-PTC), and 7 of 7 (100%) with follicular thyroid cancers (FTC) had restored RAI avidity following RDT using dabrafenib/trametinib (7 for BRAF mutant disease) or trametinib monotherapy (12 for RAS mutant disease). All 11 (100%) RAS mutant tumors (2 PTC, 3 FV-PTC, and 6 FTC) had RAI avidity restoration compared to 7 (36%) with BRAF mutant disease (6 PTC, and 1 FV-PTC). Of the 19 patients (57%) with restored RAI avidity (responders), 18 (94%) received I-131 with a median dose of 294 mCi. The median thyroglobulin (Tg) in responders was 294 mIU/L as compared to 29 mIU/L in non-responders. Following RDT-facilitated I-131 treatment, 94.7% achieved RECIST defined objective response (complete or partial response, stable disease, non-complete response/non-progressive disease) with a median progression free survival of 18 months and an overall survival of 30 months. Overall, patients with FTC (p=0.01), RAS mutation (p<0.001), Tg of 294 mIU/L or more (p=0.03), largest tumor diameter of 1.7 cm or less (p=0.05), bone metastasis (p=0.007), and without locoregional nodal disease (p=0.04), were more likely to demonstrate restored RAI avidity following RDT. Of the entire cohort, 2 (6%) patients experienced histologic transformation to anaplastic thyroid cancer and 5 (15%) patients died, all had had RAI restoration and received high-dose RAI following RDT. Conclusion: RDT has the potential to restore RAI avidity and induce RECIST responses following I-131 therapy in select patients with RAIR-DTC, particularly those with RAS mutations and ‘follicular’ phenotypes. Further studies are needed to better characterize the long-term survival and/or safety outcomes of high-dose RAI following RDT, particularly whether it could be associated with histologic transformation. Presentation Date: Saturday, June 17, 2023

Abstract Disclosure: L. Rahimi: None. A. Kittithaworn: None. R. Gregg Garcia: None. J. Saini: None. P. Dogra: None. E. Atkinson: None. S. Achenbach: None. A. Kattah: None. I. Bancos: None. Objective: Patients with mild autonomous cortisol secretion (MACS) have been reported to have a higher prevalence of chronic kidney disease (CKD), possibly due to the direct effect of hypercortisolism on kidney function and indirect effect of MACS-associated cardiovascular comorbidities, such as diabetes, hypertension, obesity, and dyslipidemia. Limited studies suggest improvement of kidney function following adrenalectomy in patients with MACS. In this study, we aimed to assess the factors associated and the degree and timing of change in kidney function post adrenalectomy in patients with MACS or nonfunctioning adrenal adenoma (NFA). Methods: We conducted a retrospective single-center study and included adult patients with MACS or NFA diagnosed based on a post-dexamethasone cortisol cutoff of 1.8 mcg/dL, who underwent adrenalectomy between 1999-2022. The change in estimated glomerular filtration rate (eGFR) before and up to 3.5 years after adrenalectomy was defined as the primary outcome. Demographics and comorbidities were included in univariable and multivariable analyses. Results: We included 155 (76.0%) patients with MACS and 49 (24.0%) patients with NFA treated with adrenalectomy. The proportion of women was high in both MACS and NFA (71.6% vs 69.4%, p=0.77), however, patients with MACS were older (median age 59.2 vs 54.6 years in NFA, p=0.05). The prevalence of hypertension was higher in MACS vs NFA (71.0% vs 53.1%, p=0.02), while the prevalence of diabetes (25.2% vs 28.6%, p=0.89), dyslipidemia (47.7% vs 46.9%, p=0.92), smoking (74.2% vs 68.9%, p=0.49) and obesity (median BMI 30.4 vs 31.8 kg/m2, p=0.35) was similar between the two groups. Prior to adrenalectomy, patients with MACS had lower eGFR (median 84.4 vs 89.2 ml/min/1.73m2, p=0.09) and a higher prevalence of CKD stage ≥ 3 (16.1% vs 8.2%, p= 0.16). In patients with MACS, after an initial decline of eGFR within 6 months post adrenalectomy (mean decrease 5.3 ml/min/1.73m2), eGFR increased by a mean of 4.9 points at 18-30 months, and by a mean of 8.1 points at 30-42 months post-adrenalectomy (p<0.01). Patients with NFA followed a similar eGFR change trend (p=NS). When comparing post-adrenalectomy delta eGFR in patients with MACS vs NFA, no significant differences were found. After adjusting for age, sex, pre-adrenalectomy eGFR, patient group, hypertension, antihypertensive therapy, and diabetes, there were still significant changes in eGFR over time. In a multivariable analysis, younger age (est -031, p<0.001) and lower pre-adrenalectomy eGFR (est-0.27, p=0.001) were associated with kidney function improvement post-adrenalectomy. Conclusion: Patients with MACS and NFA demonstrate improvement of eGFR over the 3.5 years of follow up post-adrenalectomy. The factors that are associated with improvement of eGFR are lower eGFR before surgery, younger age at time of adrenalectomy and longer follow up post adrenalectomy. Presentation: Friday, June 16, 2023

Abstract Disclosure: H.S. Abu-Lebdeh: None. H.M. Heshmati: None. Background: Prostate cancer is among the most common malignancy in men and represents the second most common cause of cancer-related mortality among men in the US. Androgen-deprivation therapy with surgical or medical castration is widely used to treat hormone-sensitive prostate cancer. Disease progression despite androgen-deprivation therapy is a state defined as castration-resistant prostate cancer that is associated with poor survival rate. This review presents an update on the contribution of two adrenal androgens, 11-ketotestosterone and 11-ketodihydrotestosterone, to the castration-resistant prostate cancer. Methods: A systematic search of literature was conducted using the search terms prostate cancer, testosterone, dihydrotestosterone, adrenal androgens, 11-ketotestosterone, 11-ketodihydrotestosterone, androgen-deprivation therapy, castration, and castration-resistant prostate cancer. Results: In 2022, around 268,490 new cases of prostate cancer were diagnosed in the US with a mortality of 34,500 cases. Although androgen-deprivation therapy with castration is efficient at the beginning, most patients develop a state of castration resistance usually after 2-3 years as a result of the reactivation of androgen-receptor signaling despite low testosterone levels. The adrenal glands produce significant amounts of steroid hormones and metabolites. Among them, 11-ketotestosterone and 11-ketodihydrotestosterone are potent and efficacious androgens with potentially longer activity compared to testosterone and dihydrotestosterone because they are metabolized at a lower rate. Dihydrotestosterone derived from the metabolism of adrenal androgens (e.g., androstenedione and dehydroepiandrosterone) and especially 11-ketotestosterone and 11-ketodihydrotestosterone are important contributors to castration-resistant prostate cancer. In these cases, adrenal suppression with drugs causing a decrease in adrenal androgen production may improve the effectiveness of the androgen-deprivation therapy. Conclusion: In most patients with prostate cancer, androgen-deprivation therapy loses its effectiveness after 2-3 years leading to a state of castration-resistant prostate cancer. Two potent and highly efficacious androgen-receptor agonists of adrenal origin, 11-ketotestosterone and 11-ketodihydrotestosterone, are predominant androgens after castration and play an important role in the development and progression of castration-resistant prostate cancer. Their measurement in blood can be of clinical value during androgen-deprivation therapy. Concomitant treatment aimed to block the production of adrenal androgens is of potential interest in the management of these patients, but more studies are necessary to further investigate the benefits and adverse effects of this approach. Presentation: Saturday, June 17, 2023

Abstract Disclosure: S.M. Alheraki: None. M.H. Horani: None. F.Z. Alharraki: None. Cushing syndrome is one of the endocrine diseases that is mainly due to the high levels of cortisol. An overproduction of adrenocorticotropic hormone (ACTH) by a pituitary adenoma or an ectopic, paraneoplastic foci (small cell lung cancer) is the primary cause of secondary hypercortisolism. While small cell lung cancer and carcinoids cause the majority of ectopic ACTH syndromes, in this article, we describe a case of Cushing syndrome secondary to lung adenocarcinoma. It is highly likely that patients with malignancies are suffering from ectopic ACTH syndrome if they exhibit clinical signs such as weakness, hypertension, or lab values indicating hyperglycemia, hypokalemia, or metabolic alkalosis. Presentation: Friday, June 16, 2023

Abstract Disclosure: M. Salama: None. S. Kumar: None. F. Pinto e Vairo: None. R. Hentz: None. Objective: The association between disrupted melanocortin 4 receptor (MC4R) pathway function and childhood obesity is well established. Several variants in MC4R pathway related genes have been implicated to influence cardiometabolic parameters including lipid metabolism and glucose homeostasis. We compared the cardiometabolic risk markers in children with obesity and MC4R related clinically reported genetic variants relative to children with obesity and no MC4R related genetic variants. Methods: This was a retrospective case-control study conducted by chart review of children (age <18 years) with obesity who underwent a multi-gene panel testing for monogenic obesity between February 2020 and November 2022. Children were divided into two groups according to their genetic test results: The first group was of children with clinically reported variants (pathogenic, likely pathogenic, risk allele or variant of uncertain significance) within the MC4R pathway), and the second group was of children with no reported variants in the MC4R pathway (negative genetic testing or variants in non-MC4R related genes). Data on systolic and diastolic blood pressure percentiles, fasting lipid panel, fasting blood glucose, hemoglobin A1c and ALT were extracted. Tests for group differences were performed using the independent two-sample t-test, Wilcoxon rank-sum test, Chi-Square test, or Fisher’s exact test as appropriate for each variable type and test assumptions. Results: Data on a total of 91 children were reviewed. Mean age at testing was 11 years (SD: 4) and mean peak BMI% of the 95th percentile was 158 (SD: 28). 36 patients had clinically reported variants in the MC4R pathway, and 55 patients had no reported MC4R related variants. The blood pressure percentiles, fasting glucose, hemoglobin A1C, total cholesterol, high density lipoprotein cholesterol and low-density lipoprotein cholesterol were not different between both groups. Conclusion: In this pilot study, among children with obesity, variants in the MC4R pathway related genes were not associated with cardiometabolic risk markers. Larger studies are warranted to assess the correlation between MC4R pathway genes and cardiometabolic risk. Presentation: Friday, June 16, 2023

Abstract Disclosure: S. Fansa: None. W. Ghusn: None. E. Tama: None. B. Nicolalde: None. D. Anazco: None. S. D'Andre: None. S. Faubion: None. C. Shufelt: None. A. Acosta: None. M.D. Hurtado: None. Background: Aromatase inhibitors (AIs) block estrogen synthesis and are used as adjuvant treatment for breast cancer. AIs are associated with weight gain that can lead to increased cardiometabolic risk, thereby affecting health and survivorship quality in these patients. The role of anti-obesity medications (AOMs) in patients using AIs has not been studied. We sought to investigate weight loss outcomes to AOMs in patients taking AIs for breast cancer treatment. Methods: This is a matched case-control retrospective cohort study of breast cancer survivors on AI using FDA-approved AOMs (AI/AOM group). We compared their weight loss outcomes with a group of female patients with obesity, without a history of breast cancer or AI use, on AOMs (AOM group). We matched patients by age and body mass index (BMI). Exclusion criteria: AOM initiation prior to AI therapy, ≤3 months of AOM use, history of bariatric surgery, active malignancy, or pregnancy. Primary endpoint: total body weight loss % (TBWL%) at 12 months. Secondary endpoints: TBWL% at 3 and 6 months and % of patients achieving categorical TBWL ≥5%, ≥10% and ≥15% at 12 months. We used Pearson χ2 and unpaired t-test to compare baseline characteristics and outcomes between groups, and univariate analyses to estimate the contribution of variables to TBWL% in the AI/AOM group. We present results as mean ± standard deviation. Results: We included 99 patients: 63 in the AI/AOM group (63.5±10 years, BMI 34.4±7.0 kg/m2) and 36 in the AOM group (60.4±8.7 years, BMI 36.3±6.9 kg/m2). Liraglutide, semaglutide and phentermine were the only AOMs used. There was no difference in the frequency of use of these three AOMs among both groups (p= 0.1). AI/AOM group had a lower TBWL% compared to the AOM group during follow-up: 3.7± 4.3% vs. 5.6 ± 4.1% (p= 0.03) at 3 months, 3.9± 4.3% vs. 9.5± 4.7% (p< 0.0001) at 6 months, and 5.2± 5.3% vs. 10.5± 6.8% (p< 0.0001) at 12 months. Although the AI/AOM group was more likely to use lower doses of AOMs (p= 0.0004), TBWL% differences persisted among groups at 12 months after adjusting for AOM dosing (p< 0.0001). There was no difference in nutritional and behavioral modification sessions among groups (p=0.06 and p=0.9, respectively). At 12 months, the percentage of patients achieving ≥5%, ≥10%, and ≥15% TBWL was greater in the AOM group compared to the AI/AOM group: ≥5% TBWL, 85.7% vs. 50.0% (p< 0.0001); ≥10%, 57.1 vs. 20.0% (p< 0.0001); and ≥15%, 28.6 vs. 5.0% (p< 0.0001); respectively. We found no predictors of TBWL% at 12 months in the AI/AOM group. Conclusion: Weight loss outcomes in breast cancer survivors on AIs taking AOMs are poorer compared to patients without breast cancer history and not taking AIs. Studies are needed to assess the mechanisms behind the different weight loss response to AOMs in women taking AIs, which we hypothesize may relate to AIs’ anti-estrogenic effect on lean and fat mass. Presentation: Friday, June 16, 2023

Abstract Disclosure: S. Fansa: None. W. Ghusn: None. B. Nicolalde: None. D. Anazco: None. E. Tama: None. A. Acosta: None. M.D. Hurtado: None. Introduction: The increasing prevalences of obesity and type 2 diabetes (T2D), the “twin epidemics”, have led to the development of drugs targeting both diseases simultaneously. Liraglutide and semaglutide, GLP-1 receptor agonists used for T2DM, are also FDA-approved for weight loss. Tirzepatide, a novel dual GIP/GLP-1 receptor agonist approved for T2D, has shown promising weight loss outcomes in clinical trials. To date, no study has assessed weight loss outcomes of tirzepatide in a real-world setting. Our aim is to assess its efficacy and safety in patients with overweight or obesity. Methods: This is a retrospective cohort study of adults with overweight or obesity taking weekly subcutaneous tirzepatide for T2D or off-label for weight loss. We excluded patients taking tirzepatide for less than one month, prior bariatric procedure, use of any anti-obesity medications, and active malignancy or pregnancy. The primary outcome was total body weight loss percentage (TBWL%) at 3 months. Secondary outcomes included TBWL% at 1 and 2 months; TBWL% difference by T2D status (with and without) and by sex at 3 months; proportion of patients achieving ≥5%, ≥10%, and ≥15% of TBWL% at 3 months; predictors of TBWL% at 3 months; and reported side effects during follow up. We used paired t-test to assess TBWL% compared to baseline, non-paired t-test to compare TBWL% by T2D status and sex, and univariate analyses to estimate the contribution of other variables to TBWL%. Results are presented as mean ± standard deviation. Results: We included 175 participants (81% female, age 49.8±12.2, 91% white, BMI 38.8±7.3 kg/m2). One third of patients had T2D (n=59, 34%). Most patients were on 5mg (39%) or 7.5mg (22%) of tirzepatide weekly. TBWL% at 1, 2, and 3 months was 3.6±2.5% (n=87), 5.8±3.5% (n=100), and 8.4± 4.3% (n=60), respectively (p <0.0001 compared to baseline at all timepoints). Patients with T2D lost less weight at 3 months compared to patients without T2D: 6.9±4.0% vs. 9.1±4.4% (p= 0.03). At 3 months, TBWL% was greater in females, 9.2±4.3% vs. 5.0±2.5% for males, p<0.0001. Greater baseline weight was associated with greater TBWL% (R=0.32, p<0.0001). At 3 months, 60 patients had documented weights with 81.6% achieving ≥ 5%, 30% achieving ≥10%, and 10% achieving ≥15% TBWL. Forty participants (23%) reported side effects. The most frequent were nausea/vomiting (n=27, 15%), constipation (n=6, 3%), and abdominal pain (n=5, 3%). Eight patients (5%) had to either decrease dosage or discontinue the drug due to side effects. Conclusion: In this retrospective cohort study, tirzepatide led to substantial weight loss at 3 months. Patients with T2DM lost less weight than patients without. Further real-world studies with longer follow-up duration and higher tirzepatide doses are needed to establish the long-term efficacy, safety, and tolerability of this drug in this setting. Presentation: Friday, June 16, 2023

Abstract Disclosure: M. Dhanasekaran: None. A.A. Rajwani: None. M.R. Castro: None. J.C. Morris: None. J. Schmitz: None. R.A. Lee: None. M. Callstrom: None. M. Stan: None. Context: Autonomously functioning thyroid nodules (AFTNs) constitutes 5% of thyroid nodules and is the second most common cause of hyperthyroidism following Graves’ Disease. Untreated hyperthyroidism is associated with adverse cardiovascular and skeletal complications. Currently, radioactive iodine (RAI) and surgery are the standard treatment options for AFTNs, and both incur a risk of post-procedural hypothyroidism. To overcome this and other surgery/radiation-related complications, radiofrequency ablation (RFA) has been utilized in multiple countries (for both toxic and non-toxic thyroid nodules). It has been shown to induce significant nodule volume reduction along with restoration of normal thyroid function in many AFTNs. Methods: We present a single-center experience using RFA as an alternative treatment modality for AFTNs. The study's primary aim was to assess the efficacy of RFA in normalizing thyroid hormone concentration and restoring the euthyroid state. In addition, we analyzed the efficacy of RFA in nodule volume rate reduction (VRR) and its associated adverse events. Results: A total of 22 consecutive patients (17 F and 5 M) underwent RFA for a solitary AFTN (hot nodule in thyroid uptake and scan) under variable degrees of general anesthesia. 72% (n=16) had subclinical hyperthyroidism, 9% (n=2) had overt hyperthyroidism, and 18% (n=4) were biochemically euthyroid on anti-thyroid drugs (ATD). The mean age at the time of ablation was 52.09 years (SD= 14.6), with a mean BMI of 27.36 kg/m2 (SD= 4.67). Average pre-treatment TSH was 0.41 mIU/L (SD= 0.980) and free T4 1.29 ng/dl (SD= 0.33). The thyroid function was assessed after a single RFA session. TSH normalized in all patients within 3-6 months following the ablation. All four patients on ATD pre-treatment discontinued therapy within three months following the procedure. The average VRR (62.54%) was achieved within 3-6 months following the RFA, and importantly, none of the nodules grew back during the follow-up period (up to 24 months). Two patients (9%) developed transient tachycardia requiring short-term beta-blocker therapy, and two (9%) developed mild hypothyroidism requiring levothyroxine therapy. One patient, euthyroid post RFA, developed recurrent hyperthyroidism 45 months later and elected to undergo lobectomy. No serious adverse effects were noted in this cohort. Conclusions - RAI and/or surgery represent the standard of care for toxic adenomas but RFA shows excellent efficacy along with an excellent safety profile. Therefore at centers with RFA expertise it should be considered an alternative treatment strategy, avoiding radiation and surgery-related complications. Presentation Date: Saturday, June 17, 2023