High Doses Of Radioactive Iodine Research Articles

Minimally Invasive Open Bilateral Total Thyroidectomy Using Unilateral Neck Incision in Thyroid Cancer: Preliminary Surgical and Quality of Life Outcomes.

Thyroid cancer incidence has increased in recent decades, and thyroid surgery is continuously evolving in response to demands for postoperative comfort and cosmesis. This study aimed to introduce a new surgical method for minimally invasive open bilateral total thyroidectomy (MI-BTT) using a unilateral 2.5-3.0 cm neck incision. Furthermore, we reported the surgical outcomes and postoperative quality of life (QoL) using a validated Korean translated Dermatology Life Quality Index (DLQI) questionnaire. We retrospectively evaluated 41 Asian patients who underwent MI-BTT for low-risk papillary thyroid cancer by a single surgeon from March 2019 to December 2021. A total of 4 male and 37 female patients were included. The mean age and body mass index were 46.2±10.1 years and 23.3±3.3 kg/m², respectively. The average tumor size was 1.1±0.6 cm, and 36 patients (87.8%) had bilateral cancer. Twenty-three (56.1%) patients had occult central lymph node (CLN) metastasis in the final pathologic report, with the mean number of dissected CLNs being 7.2±6.5. Gross capsular extension was found in 6 patients (14.6%). Moreover, 28 patients (68.3%) received additional treatment after surgery with low or high doses of radioactive iodine. The average serum-stimulated thyroglobulin value identified during treatment was 1.57±2.30 ng/mL. The mean operation time was 78.0±13.9 minutes, and postoperative complications included transient hypocalcemia (36.6%), transient hoarseness (24.4%), and seroma (2.4%). The mean total DLQI score was 2.73±0.78, indicating a small effect on QoL. MI-BTT is a novel, safe, and feasible technique to improve patient satisfaction for surgical scars and QoL.

Role and effectiveness of radioactive-iodine therapy for the treatment of Grave's disease

Le traitement de la maladie de Basedow repose sur trois thérapies: le traitement médical par les antithyroïdiens de synthèse, la chirurgie et l´irathérapie. L´objectif de notre étude était d´étudier la place et l´efficacité du traitement à l´iode radioactif dans le traitement de la maladie de Basedow. Une étude rétrospective portant sur 54 patients suivis pour une maladie de Basedow et traités par iode 131. On a mené en une étude descriptive des aspects épidémiologiques, cliniques, para cliniques et thérapeutiques et du le taux de rémission à court et à moyen terme. Le sex-ratio était de 0,45. L´âge moyen est de 38,33 ± 12,7 ans. Les signes fonctionnels les plus fréquemment retrouvés étaient l´amaigrissement, les tremblements et les palpitations. La FT4 moyenne est de 54,51 ± 19,56ng/dl (extrêmes: 8,90-100). La TSHus moyenne de nos patients était égale 0,074 ± 0,29 µUI/ml. Les antithyroïdiens de synthèse ont été prescrits chez 49 patients avec une persistance d´une hyperthyroïdie dans 83,67% des cas. L´irathérapie a été prescrite en première intention dans 9,3% et en 2ème intention dans 90,7% des cas. L´activité moyenne était égale à 13,29 mCi±1,46 avec des extrêmes allant de 10 à 15 mCi. Le premier contrôle hormonal post-irathérapie, réalisé après un délai moyen de 1,91 mois, a montré une rémission (eu- ou hypo-thyroïdie) chez 29 patients soit 53,7%. Après 12 mois de suivi, l´évolution était marquée par une rémission dans 88,88% (euthyroïdie chez 14,8% et l´hypothyroïdie chez 74%). L´irathérapie est un traitement efficace de la maladie de Basedow. Une dose forfaitaire forte d´iode radioactif permet d´obtenir un taux de rémission élevé.

Low-dose radioiodine therapy for patients with intermediate- to high-risk differentiated thyroid cancer.

The efficacy of low-dose radioiodine therapy (RIT) for intermediate-risk or high-risk differentiated thyroid cancer (DTC) patients is controversial. Because of the country's shortage of medical facilities for RIT, 1110-MBq RIT for higher risk DTC patients has been performed on an outpatient basis since 2010 in Japan. Herein, we addressed this issue and attempted to determine prognostic factors for the prediction of RIT outcomes. We retrospectively analyzed the cases of 119 patients with papillary thyroid cancer who underwent their first RIT with 1110MBq radioactive iodine (RAI) following a total thyroidectomy, including 65 (54.6%) intermediate-risk and 54 (45.4%) high-risk patients (according to Japan's 2018 clinical practical guidelines for thyroid tumors). Successful ablation was defined when a negative I-131 whole-body scan and thyroglobulin (Tg) < 2ng/mL were obtained at a diagnostic scan performed 148-560days (median 261days) after the first RIT. The overall ablation success rate was 23.4%. Although the ablation success rates of each pretreatment protocol [recombinant human thyroid stimulating hormone and thyroid hormone withdrawal (THW)] did not differ significantly, THW tended to result in a higher success rate than rhTSH. The Tg level at RIT was the only independent powerful predictive factor for successful ablation. The best cut-off value of Tg for predicting unsuccessful ablation was 9ng/mL. The ablation success rate was much lower than those of earlier studies; the most plausible reason would be that higher risk DTC patients were included in this study. The low-dose RIT routinely performed in Japan might be inadequate for the achievement of successful ablation. At least for patients with Tg > 9ng/mL at the first RIT, a higher dose of RAI is recommended.

MON-559 Inappropriate Dosing of I-131 in Non-Metastatic Differentiated Thyroid Cancer

Differentiated thyroid cancer (DTC) accounts for the majority of thyroid cancers. While radioactive iodine (RAI) treatment after thyroidectomy plays an adjunctive role in some patients, the majority of patients with DTC at our institution receive RAI. The dosing of RAI is mostly empiric. A low dose of 30 mCi of I-131 is generally favored over higher doses in low or intermediate risk disease with lower risk features while higher doses may need to be considered for high risk patients (Haugen et al.). Higher rates of nausea, neck pain, lacrimal and salivary gland dysfunction and altered taste have been described for 100 mCi of I-131 compared with 30 mCi (Schlumberger et al. and Mallick et al.). The aim of this study was to determine the average dose of RAI for DTC and to identify the risk factors in low risk patients who received high dose of 131-I (≥100 mCi) at our tertiary care institution. Methods: This was a retrospective study of 33 patients with DTC who underwent RAI treatment from January 2015-May 2018 at a single academic medical center. Data were collected from the Nuclear Medicine department. Patients over the age of 18 with a documented non-metastatic DTC diagnosis were included. Patients who received RAI at an outside facility or with no pathology report were excluded. Results: Post-operative ultrasound was not routinely performed, and only 30% of patients had a neck US before RAI dose administration. The average dose of I-131 was 75.7 mCi regardless of the American Thyroid Association (ATA) risk. Sub-analysis per ATA risk group for the average dose showed 64.7 mCi in the low risk group, 98.9 mCi in the intermediate risk group, and 95.9 mCi in the high-risk group. The tertile ranges for the RAI dose were: T1: 29-33, T2:79-115 and T3:150 mCi. 63% of patients in the low risk group received a low dose of I-131(29-33m Ci), 22 % received 79-115 mCi and 13 % received 150 mCi. In the intermediate risk group 28% received 29-33 mCi and 28% received high dose 150 mCi while 42% received 79-115 mCi. In the high-risk ATA group 25% received a low dose of I-131with 29-33 mCi. Patients in the low risk group who received more than 30 mCi but less than 150 mCi showed no high-risk features with undetectable Tg level and no high risk histopathologic features or significant lymphadenopathy. However, of the patients in the low risk group who received ≥150 mCi, 75% had an elevated stimulated Tg level > 10 ng/ml and only one patient had a post-operative neck ultrasound that showed residual tissue. Conclusion: In this small cohort, patients with non-metastatic DTC received intermediate to high doses of RAI regardless of the ATA risk. More than 1/3 of patients in the low risk group received more than the recommended RAI dose per ATA guidelines. Despite the obvious multiple benefits of RAI post-operatively, selective criteria should be used to avoid unnecessary exposure of high dose RAI that may carry additional risk both in the short and long term.

Predictors of recurrent thyrotoxicosis in a cohort of Egyptian thyrotoxic patients treated with radioactive iodine

Background The use of radioactive iodine (RAI) in the treatment of thyrotoxicosis is increasing either in recurrent cases or as first-line therapy. RAI has the advantages of being relatively inexpensive, reliable, safe, easy to administer, and highly effective. Objective The purpose of this retrospective study is to assess the efficacy of RAI in the treatment of hyperthyroidism and to determine the different prognostic factors that affect the outcome. Patients and methods Our cohort include 60 patients with hyperthyroidism who were treated with RAI in the Nuclear Medicine Unit, Mansoura University Hospital and Internal Medicine Hospital during the period from 2009 to 2015 inclusive. Patients’ records were reviewed for the following data: age, gender, history of antithyroid medications (antithyroid drugs), size of the gland, cause of hyperthyroidism (Graves’ disease, and multiple and single functioning nodules), level of fT4, and dose of RAI. Results There was female predominance of hyperthyroidism with a female to male ratio of 4.5 : 1. Sixty percent of patients were less than or equal to 50 years and 71.7% received antithyroid medications. Thyroid gland was moderately or markedly enlarged in 55% of patients. A high level of fT4 (>4 ng/ml) was recorded in 56.7%. Graves’ disease was the most common pathological diagnosis. Most patients (68.3%) received a higher dose of RAI (≥10 mCi). After 6 months of RAI therapy; hypothyroidism was observed in 29 patients (48.3%) while 12 were euthyroid (20%). Hypothyroidism was higher in Graves’ disease than other causes of thyrotoxicosis (P=0.04), while patients who have previously received antithyroid medications were less likely to develop it (P=0.04). Response to RAI was significantly higher in those with a low level of fT4 (P=0.03), small size of the gland (P=0.02), and higher dose of RAI (P=0.02). Efficacy of RAI was not dependent on age (P=1) and gender (P=1). Conclusion Our results of this study of a cohort patient with thyrotoxicosis demonstrated that the size of the thyroid gland, the dose of RAI, use of antithyroid drugs, the cause of thyrotoxicosis, and the level of fT4 significantly affect the response to RAI, while the age and gender do not. So we should appreciate these factors when planning the treatment of such cases.

Outcomes Following Fixed Dose Radioactive Iodine Therapy (RAI) in Hyperthyroid Patients with Grave’s Disease and Toxic Nodular Disease

Background: Radioactive iodine (RAI) is a definitive treatment for hyperthyroidism, but administered doses vary between institutions. We utilize a fixed dose RAI treatment protocol, administering 370MBq to all patients unless there is a large goitre present. We aimed to determine treatment outcomes following fixed dose RAI at our centre. Methods: We retrospectively reviewed thyroid function at 1 year following RAI therapy in 166 consecutive hyperthyroid patients who had been treated with 370MBq RAI between January 2001 and March 2015. Patients were stratified into 2 aetiological groups: Grave’s disease (GD) and toxic multinodular goitre (TMNG)/toxic adenoma (TA) for comparison. Results: 166 patients received 370MBq RAI over the period specified. 88 patients had GD (53%) and 70 patients had TMNG/TA (42%). Aetiology was not specified in 8 patients (5%). Patients with GD were younger 46.1±1.5 years (mean±SEM)) compared to those with TMNG/TA (63.3±1.4 years, p<0.001) and there were more female than males in both groups (80% female in GD and 84% in TMNG/TA, p=0.445). At one year post-RAI, more patients with GD were rendered hypothyroid compared to TMNG/TA (55% vs. 17%) and fewer patients with GD were rendered euthyroid (34% vs.63%) or had persistent hyperthyroidism compared to those with TMNG/TA (11% vs 20%) (p<0.001). Conclusion: When compared to GD group, proportionally more TMNG/TA patients remained hyperthyroid a year following a single dose of 370Mbq RAI. TMNG/TA patients were more likely to be euthyroid at one year post RAI, however. These results suggest that a higher dose of RAI may be needed for TMNG/TA.

Change in Practice over Four Decades in the Management of Graves' Disease in Scotland.

There is continuing debate on the optimal treatment for Grave's thyrotoxicosis with a resultant variation in clinical practice. The present study aimed to ascertain changes in practice in the treatment of Grave's thyrotoxicosis in Tayside, Scotland, over the past four decades. Methods. The “Scottish automated follow-up register” (SAFUR) was queried to identify all patients treated for Grave's thyrotoxicosis from 1968 to 2007 inclusive. Patients were divided into 4 groups (Groups A to D) according to the decades. Demographic profile, treatment modalities, radioactive iodine (RAI) dose, and recurrence rates were studied and outcomes were compared by χ 2 test and ANOVA using SPSS v15.0. A p value of < 0.05 was considered significant. Results. Altogether, 3737 patients were diagnosed with Grave's thyrotoxicosis over the 4 decades. Use of RAI has increased from 43.1% in Group A to 68% in Group D (p < 0.001). The dose of RAI has increased (p < 0.001) and there has been a reduction in recurrence rate with higher dose of RAI. Surgical intervention rates decreased from 55.3% to 12.3% (p < 0.001) over time. Conclusions. Analysis of a large dataset of patients with Grave's thyrotoxicosis suggests increasing use of RAI as the preferred first line of treatment. Furthermore, using a single higher dose of RAI and adoption of total thyroidectomy have decreased recurrence rates.

Complete Blood Counts are Frequently Abnormal 1 Year after Dosimetry-Guided Radioactive Iodine Therapy for Metastatic Thyroid Cancer

Radioactive iodine (RAI) has been associated with hematologic abnormalities. Previous research has shown that even a single dose of RAI can cause changes in the peripheral complete blood count (CBC). It is unclear if the use of dosimetry guidance would prevent the effects of high doses of RAI on bone marrow suppression. CBC at baseline was compared to a CBC obtained 1 year after the last RAI treatment in 50 thyroid cancer patients that received ≥250 mCi RAI during the course of their disease. Cumulative dose, number of treatments, patients' age, and the use of external beam radiation therapy (EBRT) were considered in the analysis. We observed a small but statistically significant decrease in hemoglobin (Hb), hematocrit (Hct), and platelet (Plt) counts at 1 year in 50 patients who had received ≥250 mCi RAI. We did not find a significant change in white blood cell count (WBC). Approximately 60% of patients who developed anemia had concomitant WBC and Plt abnormalities. RAI dose, number of treatments, and age at diagnosis did not confer a higher risk of bone marrow suppression. High cumulative activities of RAI administered under dosimetric guidance are associated with a small but statistically significant decreases in Hb, Hct, and Plt counts. The clinical implications of these changes, if any, are unclear. The benefits obtained with high doses of RAI, when indicated, are likely to outweigh the minimal hematologic risks observed in the present study.

Changes in Ovarian Function after Radioactive Iodine among Patients with Differentiated Thyroid Carcinoma at St. Luke's Medical Center, Philippines

Objective. To determine the prevalence of menstrual and reproductive dysfunction among subjects who have undergone radioiodine treatment for thyroid carcinoma. Methodology. This study enrolled adult women with Differentiated Thyroid Carcinoma who received the treatment at age 40 years and below. Data was processed using SAS program and evaluated using Fischer’s test and Wilcoxon test. Results. The study enrolled 46 women. Three reported cycle irregularities, 4 reported changes in amount of bleeding and 1 had amenorrhea. The prevalence rate of menstrual abnormalities was 15.2%. These women received a significantly higher dose of radioactive iodine (RAI) (120 vs. 110 mCi, p = 0.0064). Eleven women tried to conceive and there were 5 births to 5 different subjects after radiation. There were no congenital anomalies and 1 miscarriage. Four women were menopausal with an average age of 44.4 years old. Conclusion. This study showed that the prevalence of menstrual disturbances after high dose radioactive iodine treatment among thyroid cancer patients is 15.2%. The affected group received a significantly higher dose of radioactive iodine compared to the unaffected group.

Follicular Adenoma and Carcinoma of the Thyroid Gland

Follicular neoplasms of the thyroid gland include benign follicular adenoma and follicular carcinoma. Currently, a follicular carcinoma cannot be distinguished from a follicular adenoma based on cytologic, sonographic, or clinical features alone. The pathogenesis of follicular carcinoma may be related to iodine deficiency and various oncogene and/or microRNA activation. Advances in molecular testing for genetic mutations may soon allow for preoperative differentiation of follicular carcinoma from follicular adenoma. Until then, a patient with a follicular neoplasm should undergo a diagnostic thyroid lobectomy and isthmusectomy, which is definitive treatment for a benign follicular adenoma or a minimally invasive follicular cancer. Additional therapy is necessary for invasive follicular carcinoma including completion thyroidectomy, postoperative radioactive iodine ablation, whole body scanning, and thyrotropin suppressive doses of thyroid hormone. Less than 10% of patients with follicular carcinoma will have lymph node metastases, and a compartment-oriented neck dissection is reserved for patients with macroscopic disease. Regular follow-up includes history and physical examination, cervical ultrasound and serum TSH, and thyroglobulin and antithyroglobulin antibody levels. Other imaging studies are reserved for patients with an elevated serum thyroglobulin level and a negative cervical ultrasound. Systemic metastases most commonly involve the lung and bone and less commonly the brain, liver, and skin. Microscopic metastases are treated with high doses of radioactive iodine. Isolated macroscopic metastases can be resected with an improvement in survival. The overall ten-year survival for patients with minimally invasive follicular carcinoma is 98% compared with 80% in patients with invasive follicular carcinoma.

Long-term carbimazole intake does not affect success rate of radioactive 131Iodine in treatment of Graves' hyperthyroidism

The aim of this study is to assess the effect of long-term antithyroid drug intake on the success rate of iodine-131 (131I) treatment of Graves' hyperthyroidism, and to explore other clinical/laboratory factors that may predict/affect the treatment outcome. Fifty-eight patients with Graves' disease were referred for radioactive iodine therapy after failure of medical treatment, which was given for at least 6 months. Antithyroid drug (carbimazole) was stopped for at least 2 days before administration of a fixed dose of 370 MBq. Treatment outcome was determined at the end of 1-year follow-up after iodine administration. Treatment success was reported if the thyroid hormonal profile indicated euthyroid or hypothyroid state. One year after 131I administration, 19% of our patients were still hyperthyroid (treatment failure), 15.5% became euthyroid and 65.5% were hypothyroid (treatment success, 81%). No statistically significant correlation was found between treatment outcome and patient's age at the time of I administration (P=0.20); duration of medical treatment before 131I administration (P=0.22) and duration of stoppage of medical treatment before 131I intake (P=0.15). In contrast, there was significant association between treatment outcome and pretreatment Tc99m-thyroid uptake (P=0.0001), thyroid size (P=0.001) and TSH level (P=0.04). Using receiver operator characteristic curve analysis, we generated a cut-off value for thyroid uptake (18%) and thyroid weight (70 g) to predict response to 370 MBq of 131I. The 18% thyroid uptake cut-off value predicted treatment outcome with 93.6% sensitivity, 100% specificity and 94.8% accuracy, whereas the 70 g thyroid weight predicted treatment outcome with sensitivity, specificity and accuracy of 80.9, 72.7 and 79.3%, respectively. Long-term carbimazole treatment will not increase the failure rate of 131I treatment in patients with Graves' disease if the drug was discontinued for at least 2 days before iodine administration. A fixed dose of 370 MBq is efficient in patients with Tc99m-pertechnetate thyroid uptake less than 18% and gland weight less than 70 g. Patients with larger goitres and/or higher thyroid uptake level will probably need a higher dose of radioactive iodine.

Salivary gland function in patients with differentiated thyroid cancer treated with high doses of radioactive iodine

Purpose/ObjectiveXerostomia is a well-recognized adverse effect of high-dose radioactive iodine treatment. This study was undertaken to determine the extent of this effect quantitatively in patients with thyroid cancer treated with I-131.Materials/MethodsSalivary gland scintigraphy was performed with Tc-99m Pertechnetate and the excretion fraction (EF) of the glands was calculated as a measure of function; measurement was performed before iodine therapy as a baseline study, and three weeks and 3 months afterwards. Clinical evaluation was also performed using a standardized subjective questionnaire.ResultsThirty-six patients (11 males and 25 females, mean age 53 years) were studied. Mean EF at 3 weeks and 3 months after radioiodine therapy was reduced compared to baseline (base 54.9%, 3 weeks 47.25%, 3 months 44.02%, p < 0.05). Loss of function was greater in parotid gland than submandibular gland (p < 0.05), confirming the higher radiosensitivity of parotid gland. There was no significant loss of function in 12 patients (33%). More salivary gland involvement was noted with increase in radioiodine dose (p = 0.07). The relation of salivary gland functional involvement with radioiodine dose was significant in submandibular glands (p < 0.005). Functional impairment was more severe in parotid glands 3 months after iodine therapy than 3 weeks, but this difference was not significant in submandibular glands. No difference was noted between the two sexes (p = 0.6). No significant relation was noted between salivary gland functional loss and age (p = 0.1). Subjective clinical data correlated with the quantitative results.ConclusionsI -131 therapy produces a significant effect on salivary glands function which is dose-related, and is more obvious in parotid glands Purpose/ObjectiveXerostomia is a well-recognized adverse effect of high-dose radioactive iodine treatment. This study was undertaken to determine the extent of this effect quantitatively in patients with thyroid cancer treated with I-131. Xerostomia is a well-recognized adverse effect of high-dose radioactive iodine treatment. This study was undertaken to determine the extent of this effect quantitatively in patients with thyroid cancer treated with I-131. Materials/MethodsSalivary gland scintigraphy was performed with Tc-99m Pertechnetate and the excretion fraction (EF) of the glands was calculated as a measure of function; measurement was performed before iodine therapy as a baseline study, and three weeks and 3 months afterwards. Clinical evaluation was also performed using a standardized subjective questionnaire. Salivary gland scintigraphy was performed with Tc-99m Pertechnetate and the excretion fraction (EF) of the glands was calculated as a measure of function; measurement was performed before iodine therapy as a baseline study, and three weeks and 3 months afterwards. Clinical evaluation was also performed using a standardized subjective questionnaire. ResultsThirty-six patients (11 males and 25 females, mean age 53 years) were studied. Mean EF at 3 weeks and 3 months after radioiodine therapy was reduced compared to baseline (base 54.9%, 3 weeks 47.25%, 3 months 44.02%, p < 0.05). Loss of function was greater in parotid gland than submandibular gland (p < 0.05), confirming the higher radiosensitivity of parotid gland. There was no significant loss of function in 12 patients (33%). More salivary gland involvement was noted with increase in radioiodine dose (p = 0.07). The relation of salivary gland functional involvement with radioiodine dose was significant in submandibular glands (p < 0.005). Functional impairment was more severe in parotid glands 3 months after iodine therapy than 3 weeks, but this difference was not significant in submandibular glands. No difference was noted between the two sexes (p = 0.6). No significant relation was noted between salivary gland functional loss and age (p = 0.1). Subjective clinical data correlated with the quantitative results. Thirty-six patients (11 males and 25 females, mean age 53 years) were studied. Mean EF at 3 weeks and 3 months after radioiodine therapy was reduced compared to baseline (base 54.9%, 3 weeks 47.25%, 3 months 44.02%, p < 0.05). Loss of function was greater in parotid gland than submandibular gland (p < 0.05), confirming the higher radiosensitivity of parotid gland. There was no significant loss of function in 12 patients (33%). More salivary gland involvement was noted with increase in radioiodine dose (p = 0.07). The relation of salivary gland functional involvement with radioiodine dose was significant in submandibular glands (p < 0.005). Functional impairment was more severe in parotid glands 3 months after iodine therapy than 3 weeks, but this difference was not significant in submandibular glands. No difference was noted between the two sexes (p = 0.6). No significant relation was noted between salivary gland functional loss and age (p = 0.1). Subjective clinical data correlated with the quantitative results. ConclusionsI -131 therapy produces a significant effect on salivary glands function which is dose-related, and is more obvious in parotid glands I -131 therapy produces a significant effect on salivary glands function which is dose-related, and is more obvious in parotid glands

Salivary gland function in patients with differentiated thyroid cancer treated with high doses of radioactive iodine

Xerostomia is a well-recognized adverse effect of high-dose radioactive iodine treatment. This study was undertaken to determine the extent of this effect quantitatively in patients with thyroid cancer treated with I-131. Salivary gland scintigraphy was performed with Tc-99m Pertechnetate and the excretion fraction (EF) of the glands was calculated as a measure of function; measurement was performed before iodine therapy as a baseline study, and three weeks and 3 months afterwards. Clinical evaluation was also performed using a standardized subjective questionnaire. Thirty-six patients (11 males and 25 females, mean age 53 years) were studied. Mean EF at 3 weeks and 3 months after radioiodine therapy was reduced compared to baseline (base 54.9%, 3 weeks 47.25%, 3 months 44.02%, p < 0.05). Loss of function was greater in parotid gland than submandibular gland (p < 0.05), confirming the higher radiosensitivity of parotid gland. There was no significant loss of function in 12 patients (33%). More salivary gland involvement was noted with increase in radioiodine dose (p = 0.07). The relation of salivary gland functional involvement with radioiodine dose was significant in submandibular glands (p < 0.005). Functional impairment was more severe in parotid glands 3 months after iodine therapy than 3 weeks, but this difference was not significant in submandibular glands. No difference was noted between the two sexes (p = 0.6). No significant relation was noted between salivary gland functional loss and age (p = 0.1). Subjective clinical data correlated with the quantitative results. I -131 therapy produces a significant effect on salivary glands function which is dose-related, and is more obvious in parotid glands

Objective estimates of the probability of developing hypothyroidism following radioactive iodine treatment of thyrotoxicosis.

Several risk factors have been shown individually to influence the outcome following radioactive iodine (RAI) therapy in the treatment of hyperthyroidism. However, no attempt has been made to determine their independent prognostic values that could be used in a regression model to provide objective estimates of the probability of developing hypothyroidism. We audited records of all hyperthyroid patients treated with first dose RAI between 1980 and 1996. Patients were aetiologically categorized into Graves' disease, solitary toxic nodule and toxic multinodular goiter. Following RAI, outcome was categorized as hypothyroidism, euthyroidism and persistent hyperthyroidism. Multiple logistic regression analysis was used to identify significant risk factors, their prognostic values and probability estimates of developing hypothyroidism in the presence of one or more of these factors. The cumulative incidence of hypothyroidism was 55.8% at 1 year and 86.1% at 10 years. Graves' disease (odds ratio: 4.29), presence of thyroid autoantibodies (odds ratio: 3.51), no antithyroid treatment given prior to RAI (odds ratio: 2.50), non-palpable goiter (odds ratio: 2.48) and high RAI dose (odds ratio: 1.90), were identified as significant independent risk factors. We then developed a predictive table that provides objective estimates of developing hypothyroidism. In the absence of all risk factors we can predict an 11.9% probability of developing hypothyroidism; this increases linearly to a 96.4% probability in the presence of all factors. These objective estimates would help in understanding the relative contributions of the known risk factors, and to predict the probability of developing hypothyroidism following RAI treatment. This would not only help patients make an informed consent for a treatment that would lead to life-long replacement therapy but may also prove useful in calculating the RAI dose that may reduce or delay the onset of developing hypothyroidism.

Lack of impact of radioiodine therapy in tg-positive, diagnostic whole-body scan-negative patients with follicular cell-derived thyroid cancer.

Several reports have suggested a benefit from radioactive iodine (RAI) therapy in Tg-positive, whole-body scan-negative patients with follicular cell-derived thyroid cancer, who were said to have high rates of visualization of uptake in metastases after therapeutic doses of RAI. We sought to evaluate the rate of visualization of RAI uptake in these patients and determine the effect of such therapy on tumor progression and Tg levels. We studied 24 consecutive patients who had been treated with high-dose RAI, four of whom had no evidence of metastasis or persistent cancer. Our results showed that four patients had some uptake in posttherapy scans: in the neck, lung, and mediastinal metastases in one patient, in the thyroid remnant in two, and in a possible neck microrecurrence in one. In 13 patients with macrometastases-tumors 1 cm or greater-tumors progressed and serum Tg increased; five have died of thyroid cancer. The disease remained stable in the seven patients with micrometastases. We concluded that in high-risk patients with follicular cell-derived thyroid cancer with high Tg levels and negative diagnostic whole-body scans, only a small number showed meaningful uptake after high doses of RAI. Therefore, widespread use of empiric RAI therapy for such patients who have a large tumor burden should not be encouraged.

The Use of Radioactive Iodine in the Management of Hyperthyroidism in Children

Graves' disease is the most common form of hyperthyroidism in childhood. Current treatment options include antithyroid medications, surgery, and radioactive iodine. Medical therapy is generally associated with long-term remission rates of less than 25% and a small risk of serious adverse reactions that include hepatic failure and bone marrow suppression. Total thyroidectomy is associated with very high cure rates and a small risk of hypoparathyroidism and recurrent laryngeal nerve damage. When radioactive iodine is used at appropriate doses, there is a very high cure rate without increased risks of thyroid cancer or genetic damage. Because of the theoretical risk of thyroid cancer after thyroid irradiation in individuals less than 20 years of age, relatively high doses of radioactive iodine should be administered to minimize residual thyroid tissue.

The use of radioactive iodine in the management of hyperthyroidism in children.

Graves' disease is the most common form of hyperthyroidism in childhood. Current treatment options include antithyroid medications, surgery, and radioactive iodine. Medical therapy is generally associated with long term remission rates of less than 25% and a small risk of serious adverse reactions that include hepatic failure and bone marrow suppression. Total thyroidectomy is associated with very high cure rates and a small risk of hypoparathyroidism and recurrent laryngeal nerve damage. When radioactive iodine is used at appropriate doses, there is a very high cure rate without increased risks of thyroid cancer or genetic damage. Because of the theoretical risk of thyroid cancer after thyroid irradiation in individuals less than 20 years of age, relatively high doses of radioactive iodine should be administered to minimize the persistence of residual thyroid tissue.

2. Patient satisfaction survey to identify the role of the nuclear medicine specialist nurse in the treatment of thyroid cancer patients receiving high doses of radioactive iodine in an isolation side-ward

2. Patient satisfaction survey to identify the role of the nuclear medicine specialist nurse in the treatment of thyroid cancer patients receiving high doses of radioactive iodine in an isolation side-ward

Effect of treatment with radioactive iodine and iodine-deficient diet on development and maintenance of renal hypertension in rats.

Treatment of kidney encapsulated rats with 850 µC. of radioactive iodine effectively prevented both the characteristic rise of blood pressure to hypertensive levels and cardiac hypertrophy. Iodine-deficient diet was ineffective under these conditions. Once hypertension was established, treatment with 850 µC. radioactive iodine lowered blood pressure toward normal levels although a significant decrease in heart weight was not observed. The iodine-deficient diet was also ineffective under these conditions. It is felt that hypothyroidism produced by administration of high doses of radioactive iodine is as effective in preventing blood pressure rise as that observed with propylthiouracil treatment. The antihypertensive effect of these antithyroid treatments appears to be the direct result of inhibition of secretion of thyroid hormone.