Radioactive iodine 1311 (RAI) treatment. The nearest to the "magic bullet" but should always be preceded by a risk assessment, especially in the pediatric patient.

Radioactive iodine treatment is very frequently the best approach, but it should be optimized by dosimetric and risk considerations.

Changes in Thyrotropin Receptor Antibody Levels Following Total Thyroidectomy or Radioiodine Therapy in Patients with Refractory Graves' Disease.

Background: The actions of thyrotropin-binding inhibitory immunoglobulins (TBIIs) against thyrotropin receptors in thyroid follicular cells have been studied as important etiological factors in Graves' disease (GD). The purpose of this study was to investigate changes in the TBII levels of patients undergoing total thyroidectomy (TTx) or radioactive iodine (RAI) therapy for GD refractory to antithyroid drugs (ATDs). Methods: We enrolled patients who underwent TTx or RAI for GD with previous ATD use between January 2011 and December 2017 at the Samsung Medical Center in Seoul, Korea. Thorough retrospective reviews of medical records were performed in 130 patients. Results: Patients with goiter, ophthalmopathy, high levels of TBIIs, and high doses of ATDs received TTx. Elderly patients with arrhythmia received RAI. We observed that TBII levels continued to decrease after TTx. On the contrary, TBIIs initially increased for 138 days (estimated median time) and then decreased slowly after RAI. A faster decline in TBII levels was observed in the TTx group than in the RAI group (p < 0.001). The estimated median time for TBIIs to decrease below 4.5 IU (3 × upper normal limit, which is known to be a risk factor for fetal hyperthyroidism) was 318 days in the TTx group and 659 days in the RAI group, respectively. In the RAI group, high levels of TBII (>4.5 IU/L) were present in 70 (82%) at 6 months, 57 (67%) at 1 year, and 3 (3%) at 2 years. In the TTx group, rapid decreases in TBII levels were observed in younger patients and those with lower baseline TBII levels. In the RAI group, smaller thyroid volume was correlated with more rapid decrease in TBII levels. Conclusions: The changes in TBII levels following TTx or RAI were different in patients with refractory GD. When deciding on TTx or RAI, this difference should be considered with patient age, severity of hyperthyroidism, goiter, ophthalmopathy, and future pregnancy plans (for young female patients).

Correction for hyperfunctioning radiation-induced stunning (CHRIS) in benign thyroid diseases.

PURPOSE: Radioiodine-131 treatment has been a well-established therapy for benign thyroid diseases for more than 75 years. However, the physiological reasons of the so-called stunning phenomenon, defined as a reduced radioiodine uptake after previous diagnostic radioiodine administration, are still discussed controversially. In a recent study, a significant dependence of thyroid stunning on the pre-therapeutically administered radiation dose could be demonstrated in patients with goiter and multifocal autonomous nodules. A release of thyroid hormones to the blood due to radiation-induced destruction of thyroid follicles leading to a temporarily reduced cell metabolism was postulated as possible reason for this indication-specific stunning effect. Therefore, the aim of this study was to develop dose-dependent correction factors to account for stunning and thereby improve precision of radioiodine treatment in these indications. METHODS: A retrospective analysis of 313 patients (135 with goiter and 178 with multifocal autonomous nodules), who underwent radioiodine uptake testing and radioiodine treatment, was performed. The previously determined indication-specific values for stunning of 8.2% per Gray in patients with multifocal autonomous nodules and 21% per Gray in patients with goiter were used to modify the Marinelli equation by the calculation of correction factors for hyperfunctioning radiation-induced stunning (CHRIS). Subsequently, the calculation of the required activity of radioiodine-131 to obtain an intra-therapeutic target dose of 150 Gy was re-evaluated in all patients. Furthermore, a calculation of the hypothetically received target dose by using the CHRIS-calculated values was performed and compared with the received target doses. RESULTS: After integrating the previously obtained results for stunning, CHRIS-modified Marinelli equations could be developed for goiter and multifocal autonomous nodules. For patients with goiter, the mean value of administered doses calculated with CHRIS was 149 Gy and did not differ from the calculation with the conventional Marinelli equation of 152 Gy with statistical significance (p = 0.60). However, the statistical comparison revealed a highly significant improvement (p < 0.000001) of the fluctuation range of the results received with CHRIS. Similar results were obtained in the subgroup of patients with multifocal autonomous nodules. The mean value of the administered dose calculated with the conventional Marinelli equation was 131 Gy and therefore significantly below the CHRIS-calculated radiation dose of 150 Gy (p < 0.05). Again, the fluctuation range of the CHRIS-calculated radiation dose in the target volume was significantly improved compared with the conventional Marinelli equation (p < 0.000001). CONCLUSIONS: With the presented CHRIS equation it is possible to calculate a required individual stunning-independent radioiodine activity for the first time by only using data from the radioiodine uptake testing. The results of this study deepen our understanding of thyroid stunning in benign thyroid diseases and improve precision of dosimetry in radioiodine-131 therapy of goiter and multifocal autonomous nodules.

The success rate of radioactive iodine therapy for Graves' disease in iodine-replete area and affecting factors: a single-center study.

OBJECTIVE: Initial treatment options for Graves' disease include antithyroid drugs, radioactive iodine (RAI), and surgery. Because of similar effects of three modalities, initial treatment preferences differ by country to country. In Korea, iodine-replete area, RAI was used as a second-line option. For these reasons, the RAI success rate in Korea might differ from other countries. METHODS: A total of 247 patients were enrolled. The primary outcome was cumulative success rate in the first year, and the secondary outcome was factors that affected the success. Delayed response, which included patients who attained successful RAI during the follow-up, after the first year without further RAI, and factors that affected the delayed response were reviewed. RESULTS: The cumulative success rate in the first year was 62.8%. Higher RAI activity [odds ratio (OR) 2.56, P = 0.02], longer disease duration (OR 0.43, P = 0.01), larger goiter (OR 0.31, P = 0.01), and higher post-RAI fT4 (fT4 between upper normal limit (UNL) to 1.5 × UNL; OR 0.24; P < 0.01, 1.5 × UNL<; OR 0.08; P < 0.01) were associated with RAI success. Twenty-seven patients showed delayed response, and goiter size (P < 0.05), pre-RAI TSH receptor Ab (TRAb) level (P < 0.01) and post-RAI fT4 (P < 0.01) were associated. CONCLUSION: The success rate of the first RAI in Korea was lower than that in other countries. Delayed response was observed in patients with smaller goiter, low pre-RAI TRAb, and low post-RAI fT4. In these patients, clinical follow-up with monitoring could be an option, and decision of optimal timing of first RAI is crucial.

Optimizing 131I uptake after rhTSH stimulation in patients with nontoxic multinodular goiter: evidence from a prospective, randomized, double-blind study.

UNLABELLED: Prestimulation with recombinant human thyroid-stimulating hormone (rhTSH) augments radioiodine (131)I therapy for benign nontoxic multinodular goiter. The purpose of this study was to determine the optimal time interval between rhTSH and (131)I administration to enhance thyroid radioactive iodine uptake (RAIU). METHODS: Patients were randomized, in a 2-factorial design, to receive either a 0.1-mg dose of rhTSH (n = 60) or placebo (n = 30) and to a time interval of 24, 48, or 72 h before (131)I administration. The rhTSH- or placebo-stimulated RAIU study was performed at 4 wk after a baseline RAIU assessment in a tertiary referral center at a university hospital. A total of 90 patients (78 women; median age, 52 y; range, 22-83 y) referred to (131)I therapy for symptomatic nontoxic goiter (median goiter volume, 63 mL; range, 25-464 mL) were included in the study. Change in thyroid RAIU was determined at 24 and 96 h after (131)I tracer administration. RESULTS: In the placebo subgroups, RAIU did not change significantly from baseline. The mean (+/-SE) 24-h RAIU increased from 33.8% +/- 2.3% to 66.0% +/- 1.8% (111.2% increase) with a 24-h interval, from 36.8% +/- 2.1% to 64.6% +/- 2.7% (83.3% increase) with a 48-h interval, and from 33.0% +/- 2.7% to 49.6% +/- 2.5% (62.4% increase) with a 72-h interval. All within-group changes were highly significant (P < 0.001). The effect was negatively correlated with initial RAIU (r = -0.703, P < 0.001). The increase in 24- and 96-h RAIU was significantly higher in the rhTSH/24-h group than it was in the rhTSH/72-h group (P = 0.023 and 0.012, respectively) and insignificantly higher than in the rhTSH/48-h group (P = 0.37 and 0.26, respectively). CONCLUSION: The effect of rhTSH on thyroid RAIU is most pronounced when administered 24 h before (131)I administration and declines with longer time intervals. Whether there is a similar time dependency for goiter reduction after rhTSH-stimulated (131)I-therapy remains to be clarified.

Prediction of cure and risk of hypothyroidism in patients receiving 131I for hyperthyroidism.

CONTEXT: There is little consensus regarding the most appropriate dose of radioiodine ((131)I) to be administered to patients with hyperthyroidism. OBJECTIVE: To compare the efficacy of fixed dose regimens of (131)I in curing hyperthyroidism and to define simple clinical and biochemical factors that predict outcome in individual patients. DESIGN: Consecutive series of hyperthyroid subjects treated with (131)I. SETTING: Single Secondary/Tertiary Care Hospital Clinic. PARTICIPANTS: A total of 1278 patients (1013 females and 262 males, mean age 49.7 years) presenting with hyperthyroidism between 1984 and 2006. INTERVENTION: Treatment with (131)I using a fixed dose regimen. MAIN OUTCOME MEASURES: Probability of cure and risk of development of hypothyroidism following a single dose of (131)I. RESULTS: Patients given a single dose of (131)I of 600 MBq (n = 485) had a higher cure rate (84.1%) compared with those receiving either 370 MBq (74.9%, P < 0.001) or those given 185 Bq (63%, P < 0.001). An increased incidence of hypothyroidism by 1 year was evident with higher doses (600 MBq: 60.4%; 370 MBq: 49.2%, P = 0.001; 185 Bq: 38.1%, P < 0.001). Binary logistic regression analysis identified a 600 Bq dose of (131)I [adjusted odds ratio, AOR 3.33 (2.28-4.85), P < 0.001], female gender [AOR 1.75 (1.23-2.47), P = 0.002], lower presenting serum free T4 concentration [AOR 1.01 (1.01-1.02), P < 0.001] and absence of a palpable goitre [AOR 3.33 (2.00-5.56), P < 0.001] to be independent predictors of cure. Similarly, a 600 MBq dose [AOR 3.79 (2.66-5.38), P < 0.001], female gender [AOR 1.46 (1.05-2.02), P = 0.02], younger age [AOR 1.03 (1.02-1.04), P < 0.001], absence of a palpable goitre [AOR 3.85 (2.38-5.88), P < 0.001] and presence of ophthalmopathy [AOR 1.57 (1.06-2.31), P = 0.02] were identified as independent factors predicting the probability of development of hypothyroidism at one year. Based on these findings, formulae to indicate probability of cure and risk of hypothyroidism for application to individual patients were derived. CONCLUSIONS: Simple clinical/biochemical criteria can be used to predict outcome after (131)I treatment. These factors determine that males, those with severe biochemical hyperthyroidism, and those with a palpable goitre require larger doses (600 MBq) in order to achieve cure.

Therapy of large multinodular goitre using repeated doses of radioiodine.

OBJECTIVE: To evaluate the efficacy of radioiodine therapy using I in a group of patients with large multinodular goitre (LMG). METHODS: The study was carried out in patients with goitre volume greater than 100 cm and in patients with LMG who were disqualified from surgery. The study included 34 female participants (age range: 62-84 years) with LMG: 26 patients were hyperthyroid and eight patients had a nontoxic goitre. The patients were treated with 800 MBq of radioiodine administered four times at 3-month intervals (total activity of 3.2 GBq). Before each therapy course, serum thyrotropin, free thyroxin, free triiodothyronine and antithyroid antibodies were measured, ultrasonography and thyroid scan were performed. Patients were followed up for a minimum of 24 months. Fine-needle biopsy was done before qualification to the study. RESULTS: Before therapy, median thyroid volume was 145 cm. It decreased during therapy to 65-76 cm after 12 months and to 50-62 cm after 24 months. After 24 months, 60% of patients were euthyroid and 40% of patients were hypothyroid. During therapy, significant increases in TSHRAb, TPOAb and TgAb levels were observed. No correlation between the levels of antithyroid antibodies, radioiodine uptake, reduction of goitre volume and hormonal status was found. CONCLUSION: In most cases of LMG, repeated administration of radioiodine is safe and effective. The highest response of the thyroid volume is observed after the first course of treatment. On account of a high incidence of hypothyroidism, the patients should be monitored during and after therapy.

Radioiodine therapy in patients with amiodarone-induced thyrotoxicosis (AIT).

INTRODUCTION: Amiodarone (AM) is frequently used in the therapy of patients with cardiac disorders. However, due to high iodine content, it has side effects on thyroid function. The use of radioiodine therapy (RIT) in amiodarone-induced thyrotoxicosis (AIT) with low radioactive iodine uptake (RAIU) is still controversial. In these patients therapeutic choices for refractory disease include surgery, antithyroid drugs, or glu ocorticosteriods. AIM: The aim of the study was to evaluate the efficacy of RIT in patients presenting AIT and low RAIU in two-year follow-up. PATIENTS AND METHODS: 40 patients (25 men and 15 women) aged from 63 to 83 years (x +/- SD: 66.2 +/- 5.0 years; median: 65 years) treated with RIT were included into the study. In these patients AM therapy was essential for the underlying heart disorder, while surgery, antithyroid drugs or glucocorticosteroids, were contraindicated. Forty seven patients with toxic multinodular goiter (TMNG) (39 women and 8 men), matched for age (67 +/- 12 yr; range 54-89 yr), were enrolled into the study as a comparative group. The diagnostic procedures included baseline thyroid function tests (thyrothropin - TSH, free triiodothyronine - fT3 and free thyroxine - fT4 levels), thyroid autoantibodies measurement (antithyroglobulin autoantibodies - TgAb, antithyroid peroxidase autoantibodies - TPOAb, anti-TSH receptor autoantibodies - TRAb), thyroid ultrasonography, thyroid scintiscan and RAIU assessment. RESULTS: Serum values of TSH, TgAb, TPOAb and TRAb were undetectable in both groups. In patients with AIT fT4 level was 18.7 to 38.7 pmol/l (mean: 27.1 +/- 5.8) and fT3 concentration was 3.9 to 5.6 pmo/l (mean: 5.7 +/- 1.4), while in TMNG patients level of fT4 was 31.5 to 22.2 pmol/l (mean: 25,3 +/- 5,8) and fT3 concentration was 3.8 to 4,2 pmo/l (mean: 4,2 +/- 0,2). Mean RAIU values after 5h and 24h in AIT patients were 2.3 +/- 0.5 and 3.1 +/- 0.9%, while in TMNG patients were 18,0 +/- 3,8 and 35,7 +/- 9,1%, respectively. A significant difference (p<0.001) between 5h and 24h RAIU in AIT compared to TMNG was noted. In all patients with AIT, a dose of 800 MBq of 131I was administered. During two-year-observation recurrence of hyperthyroidism was observed in two patients (5%) with TMNG. These patients received a second radioiodine dose 16.2 +/- 15 months later (the mean re-treatment dose was 735.93 +/- 196.1 MBq). In comparison, none of the patients with AIT required a second 131I dose and only one patient (2.5%) 6 months after ablative 131I dose needed anti-thyroid medication. Transient hypothyroidism was observed in only two patients (5%) with AIH, though was not observed in TMNG. During follow-up time, no sudden deaths in AIT patients were observed; one patient was diagnosed with prostate cancer, and in one patient acute toxic hepatitis after AM occurred. CONCLUSION: RIT may be a safe and useful method of AIT therapy in patients with low RAIU, in whom other treatment methods are contraindicated.

[Selective pituitary resistance to thyroid hormone in a patient treated with amiodarone]. / Resistencia hipofisaria a las hormonas tiroideas en un paciente tratado con amiodarona.

Selective pituitary resistance to thyroid hormones is a syndrome that involves inadequate response of thyroid-stimulating hormone to changes in thyroid hormones. Unlike generalized resistance syndromes, this entity produces central hyperthyroidism and clinical thyrotoxicosis. Sometimes the disease may not be properly diagnosed and is treated with drugs with harmful effects on the thyroid, such as amiodarone, hampering diagnosis and possibly exacerbating the disorder. The treatment of this condition can be symptomatic, based on control of tachycardia and anxiety, or etiological, acting on the pituitary to regulate thyrotropin secretion or on the thyroid gland to control thyroid hormone production. We report the case of a patient with pituitary resistance to thyroid hormone, who was treated with amiodarone to control paroxysmal atrial fibrillation.

Radioiodine treatment for benign thyroid disorders: results of a nationwide survey of UK endocrinologists.

BACKGROUND: A survey of physicians' practice relating to radioiodine administration for hyperthyroidism was carried out in the UK over 15 years ago and showed wide variations in patient management. This led to the development of national guidelines for the use of radioiodine in hyperthyroidism. As there have been significant advances in the field since that survey, we carried out another survey to study the prevalent practices relating to radioiodine therapy for benign thyroid disorders across the UK. SUBJECTS AND METHODS: We mailed 698 UK consultant endocrinologists a questionnaire on radioiodine treatment based on three patient scenarios: hyperthyroid Graves' disease, subclinical hyperthyroidism and nontoxic goitre. RESULTS: The response rate was 40%. For the scenario of an initial presentation of Graves' disease, 80%, 19% and 0.4% of respondents preferred thionamide, radioiodine or thyroidectomy, respectively. There were inconsistencies in respondents' recommendations on radioiodine dose, the use of pre- and post-radioiodine supplementary treatments, timing of a repeat dose, and the use of radioiodine in thyroid eye disease. For the case of subclinical hyperthyroidism, one-third of respondents would generally initiate treatment. The majority were more likely to treat subclinical hyperthyroidism in the presence of paroxysmal atrial fibrillation or osteoporosis. If a decision were made to treat subclinical hyperthyroidism, 63%, 35%, 1% and 0.4% would recommend radioiodine, thionamide, beta-blocker and thyroidectomy, respectively. For the scenario of nontoxic goitre, 62%, 21%, 13% and 5% favoured observation, thyroidectomy, radioiodine and thyroxine, respectively. CONCLUSIONS: There remain significant differences in several aspects of clinical practice relating to the use of radioiodine treatment for benign thyroid disorders in the UK.

Quantitative analysis of the factors responsible for over or under dose of 131 I therapy patients of hyperthyroidism.

Radioiodine (131 I) therapy has been in use for more than 60 y. Several protocols have been suggested and used for prescribing the activity to be administered to the patients for the treatment of hyperthyroidism; application of these protocols may result in an under or over dose of the hyperthyroid patients. The main objective of this study was to carry out quantitative analysis of the factors responsible for possible under or over dosage of the patients. In this regard, a total of 59 patients [15 diffuse goitre (DG) and 44 nodular goitre (NG) cases] were studied. In order to compare the thyroid doses calculated by using different protocols, the dosimetric approach was followed. 131 I uptakes were measured after 24 and 48 h, respectively, by giving 0.5 MBq of 131 I to each patient. Thyroid mass and effective half-life were also calculated for each patient and the variations in the thyroid doses were analysed. According to the results 28 and 54% patients were under dosed and 72 and 46% patients were over dosed with DG and NG, respectively. The protocols, which have not taken into account the thyroid mass, multi pre-therapeutic 131 I uptakes and the effective half-life of 131 I of the individual patient, showed a higher degree of deviation from the required thyroid dose. Besides these parameters, some fundamental factors such as radiosensitivity, previous exposure to thyroid drugs and duration of the disease are recommended to be incorporated, which can certainly affect the clinical out comes.

Improvement of goiter volume reduction after 0.3 mg recombinant human thyrotropin-stimulated radioiodine therapy in patients with a very large goiter: a double-blinded, randomized trial.

INTRODUCTION: The effect of (131)I therapy amplification by recombinant human (rh) TSH prestimulation in very large goiters has not been evaluated in a double-blinded, placebo-controlled study. METHODS: Twenty-nine patients (22 females; age range 37-87 yr) with a large multinodular goiter (median 160 ml, range 99-440 ml) were randomized to receive placebo (n = 15) or 0.3 mg rhTSH (n = 14) 24 h before (131)I administration. Goiter volume was monitored by magnetic resonance imaging. RESULTS: On average, the goiter volume was unchanged 1 wk after therapy in both groups, but the largest deviations from baseline were observed in the rhTSH group. After 12 months the median goiter volume was reduced from 170 to 121 ml in the placebo group and from 151 to 72 ml in the rhTSH group, respectively (within group: P = 0.001; between group: P = 0.019). This corresponds to reductions of 34.1 +/- 3.2 and 53.3 +/- 3.3%, respectively (between group: P < 0.001). In the placebo group, the goiter reduction correlated positively with the retained thyroid (131)I dose, whereas such a relationship was absent in the rhTSH group. Adverse effects, mainly related to thyroid pain and cervical compression, were more frequent in the rhTSH group. At 12 months, goiter-related complaints were significantly reduced in both groups without any between-group difference. One and three patients in the placebo and the rhTSH group, respectively, developed hypothyroidism. CONCLUSION: rhTSH-stimulated (131)I therapy improves the reduction of very large goiters by more than 50%, compared with (131)I therapy alone, but at the expense of more adverse effects after therapy. Our data suggest that rhTSH stimulation may work through mechanisms that go beyond the increase in thyroid (131)I uptake.

Radioactive iodine therapy for goitrous Hashimoto's thyroiditis.

CONTEXT: Hashimoto's thyroiditis is an autoimmune disease that can produce marked clinical symptoms when patients have large diffuse goiters. DESIGN: This retrospective cohort study was designed to evaluate whether radioactive iodine (RAI) is effective for Hashimoto's thyroiditis with a large goiter. Starting in November 1999, 13 Hashimoto's patients with large goiters, whose thyroiditis was refractory to TSH suppression therapy with thyroid hormone administration [two men and 11 women with a mean age of 61.2 +/- 8.9 yr (50-79 yr)], were recruited for the present study. The duration of symptomatic goiter before undergoing RAI was 12.0 +/- 7.9 yr (4-33 yr). Thirteen millicuries of 131I was administered two to six times, at an interval of 1-6 months on an outpatient basis. Thyroid weight was measured ultrasonographically, or by computed tomography if ultrasound was not possible due to the large size of the goiter. RESULTS: RAI was administered an average of 4.7 +/- 1.4 times (two to six times), with a total dose of 59.8 +/- 17.3 mCi (25.0-78.0 mCi). The observation period was 47.9 +/- 13.4 months (26-66 months) after the first RAI. The average weight of the thyroid gland was 125.3 +/- 57.7 g (42.9-269.4 g) before the first RAI, decreasing significantly to 49.7 +/- 25.8 g (18.3-93.3 g) after the last RAI (P < 0.001, paired Student's t test). The percent reduction from baseline was 58.7 +/- 14.2% (35.7-84.0%). None of the patients showed an increase in goiter size or complained of a pressure sensation after any of the RAI treatments. CONCLUSION: RAI is effective in Hashimoto's thyroiditis with a large goiter.

Radioiodine Therapy Does Not Change the Atherosclerotic Burden of the Carotid Arteries.

BACKGROUND AND AIM: Atherosclerosis evolves or accelerates when arteries are exposed to ionizing radiation, both early and late after exposure. Radioiodine therapy of benign thyroid disease exposes the carotid arteries to 4-50 Gy, and may thereby increase the risk of atherosclerosis. Increased risk of cerebrovascular events has been reported after radioiodine therapy. This study aimed to examine whether atherosclerosis develops early or late after radioiodine therapy of benign thyroid disease. METHOD: Patients treated for benign thyroid disorders (nontoxic goiter, adenoma, and hyperthyroidism) were examined with ultrasound for the main outcome, carotid intima media thickness (CIMT), and for plaque presence (plaque presence only in late damage). Signs of early damage from radioiodine were studied in 39 radioiodine-treated patients, who were examined before treatment and at 1, 3, 6, and 12 months after treatment. Late changes were studied in a cross-sectional case-control design, with radioiodine-treated patients as cases (n = 193) and patients treated with surgery as controls (n = 95). Data were analyzed with repeated measurement for longitudinal data, and with multivariate regression for cross-sectional data. Results were adjusted for age, sex, cholesterol, smoking status, known atherosclerotic disease, and body mass index. RESULTS: No changes in CIMT were found in the patients followed prospectively for one year after treatment with radioactive iodine for benign thyroid disease (p = 0.58). In the study on late effects, there was no difference in CIMT (p = 0.25) or presence of plaques (p = 0.70) between those treated with radioactive iodine and those treated with surgery (9.8 and 5.6 years since treatment, respectively). Furthermore, the level of thyrotropin (TSH) did not influence these atherosclerosis markers. CONCLUSION: No early changes in CIMT were detected in patients treated with radioactive iodine for benign thyroid disease. No signs of late effects of radioactive iodine on CIMT or plaque presence were found after 10 years of follow-up. The radiation to the carotid arteries by radioactive iodine therapy for benign thyroid disease may therefore have no or low effect on atherosclerotic burden of the carotid arteries in general.

Effect of long-term continuous methimazole treatment of hyperthyroidism: comparison with radioiodine.

OBJECTIVE: To investigate the long-term effects of continuous methimazole (MMI) therapy. DESIGN AND METHODS: Five hundred and four patients over 40 years of age with diffuse toxic goiter were treated with MMI for 18 months. Within one year after discontinuation of MMI, hyperthyroidism recurred in 104 patients. They were randomized into 2 groups for continuous antithyroid and radioiodine treatment. Numbers of occurrences of thyroid dysfunction and total costs of management were assessed during 10 years of follow-up. At the end of the study, 26 patients were still on continuous MMI (group 1), and of 41 radioiodine-treated patients (group 2), 16 were euthyroid and 25 became hypothyroid. Serum thyroid and lipid profiles, bone mineral density, and echocardiography data were obtained. RESULTS: There was no significant difference in age, sex, duration of symptoms and thyroid function between the two groups. No serious complications occurred in any of the patients. The cost of treatment was lower in group 1 than in group 2. At the end of 10 years, goiter rate was greater and antithyroperoxidase antibody concentration was higher in group 1 than in group 2. Serum cholesterol and low density lipoprotein-cholesterol concentrations were increased in group 2 as compared with group 1; relative risks were 1.8 (1.12-2.95, P<0.02) and 1.6 (1.09-2.34, P<0.02) respectively. Bone mineral density and echocardiographic measurements were not different between the two groups. CONCLUSION: Long-term continuous treatment of hyperthyroidism with MMI is safe. The complications and the expense of the treatment do not exceed those of radioactive iodine therapy.

Influence of dose rate on therapeutic success of radioiodine therapy of functional thyroid autonomy.

OBJECTIVE: To evaluate the effect of dose rate on the therapeutic success of radioiodine therapy (RIT) by retrospective analysis of two groups of patients with different dose rates during RIT. METHODS: The average dose rate until deposition of 50% of the total radiation dose achieved (the DL50 value) was calculated. Ninety patients with autonomy of the thyroid receiving radiation doses between 300 and 400 Gy were separated in groups with high DL50 values (the DL50 H group) and low DL50 values (the DL50L group). Before and 4 months after RIT free triiodothyronine (FT3), free thyroxine (FT4), basal thyroid stimulating hormone (TSHB), stimulated TSH (TSHS), thyroidal technetium uptake (TcTU), and the existence of focal abnormalities in thyroid scintigraphy were evaluated. RESULTS: The DL50 H and DL50L groups showed no differences before RIT in the parameters assessed as well as in total achieved dose and autonomous thyroid volume. After therapy a significant difference was found in TSHB with higher values in DL50 H (1.89+/-1.49 vs. 1.31+/-1.48 mU . l, P<0.05), FT4 showed a trend to lower values (13.8+/-4.0 vs. 16.1+/-6.2 pmol . l, P=0.09). CONCLUSION: The DL50 value has an influence on therapeutic success of RIT. This influence is only discrete and not likely to produce clinically relevant effects in the practical use of RIT.

Natural history of radiation-associated thyroid cancer.

The clinical courses of 91 patients with radiation-associated thyroid cancer were compared with courses in a control population. Radiation-associated carcinoma appears to be a disease of younger persons, and 90% of the tumors are papillary. No anaplastic or medullary tumors were observed. Ninety percent of the tumors were larger than those found in an autopsy series that surveyed for "biologically benign" thyroid tumors. There was a higher incidence of multicentric disease, locally invasive disease, and distant metastases in the population that had had x-ray exposure. Although the population with x-ray exposure had had more aggressive treatment, more recurrences were present in patients who had had radiation therapy. The death rate was similar in both groups. Parathyroid adenoma occurred more frequently in the population that had radiation exposure than in controls and appears to be a radiation-associated illness.

The incidence of recurrence and hypothyroidism after radioiodine treatment in patients with hyperthyroidism in Trakya, a mild iodine deficiency area, during the period 1991-2003.

OBJECTIVE: The purpose of this retrospective study was to evaluate the incidence of recurrence and the success of radioiodine treatment (RIT) in the Trakya region of Turkey, an area with mild iodine deficiency, and to compare the effect of dose regimen selection (fixed (FD) or calculated dose (CD)) on treatment success. MATERIAL AND METHODS: The study sample included 148 patients (40 male, median age 50) treated with radioiodine between the years 1991-2003. Patients were categorized into three diagnostic groups: Graves' disease (GD) (n = 65), solitary toxic adenoma (TA) (n = 29), and toxic multinodular hyperthyroidism (TMH) (n = 54), and each divided into two subgroups according to treatment method; the first group was treated with a FD of 370 MBq (10 mCi), and the second with CD. RESULTS: The largest group was GD (44%), followed by TMH (36%). Median duration of follow-up was 28 months (range 6-147). FD was given to 52.7% of all patients and CD was given to 47.3%. There was a partial difference in the dose regimen between all groups, but did not reach statistically significant levels (FD vs. CD: 65%-35%; 38%-62%; 46%-54%; GD, TA, TMH respectively, p > 0.05). Total cure rate in FD and CD was 46 (59%) and 37 (52.9%), respectively. The rates of hypothyroidism for GD, TA, and TMH groups were 28 (43.1%), 6 (20.7%) and 16 (29.6%), respectively. The incidence of hypothyroidism did not vary significantly between any groups (p > 0.05). At the end of the follow-up period, a total of 104 patients (70.3%) were treated successfully. There was no significant difference in the cure rate between any groups (p > 0.05). CONCLUSIONS: The treatment success in all groups and subgroups did not differ significantly between FD and CD. Our lower cure rate than in previous studies may be related to iodine deficiency. Higher doses of radioiodine may be required to increase final treatment success in endemic goiter areas. If this true, dosimetry and calculated dose regimen would be required in all groups of patients instead of an FD concept. However, our findings should be verified in larger series of patients, with longer follow-up period, and urinary iodine concentration measurements.

[I131 in blood samples: management in the laboratory]. / Gestion au laboratoire d'échantillons de sang de patients traités par iode radioactif.

OBJECTIVES: Patients treated by (131)I may require blood sampling in the days following its administration. We investigated the safety of such samples in terms of radioactivity and the possible disturbance of the analyses by these "131I-spiked" samples. METHOD: 1) The radioactivity of blood samples from 131I-treated patients was measured (dose rate, surface activity, total activity) ; 2) The risk for the personnel was subsequently evaluated and ; 3) The interference of this 131I-generated radioactivity on the results of routine automated and IRMA assays was investigated. RESULTS: 1) All RA measures but two were found below the European limits ; 2) Irradiation of personnel was negligible ; 3) The faint radioactivity did not disturb any analyses. CONCLUSION: These data demonstrate the safety that results from the negligible radioactivity in these blood samples.

Thyrotropin receptor antibodies and Graves' disease, a side-effect of 131I treatment in patients with nontoxic goiter.

The use of 131I treatment in patients with benign nontoxic goiter is increasing, and the described side-effects are few. In this paper we describe appearance of TSH receptor antibodies (TRAb) and concomitant development of hyperthyroidism as a side-effect of 131I treatment in patients with nontoxic goiter. In this retrospective study, 191 consecutive patients with 131I-treated nontoxic goiter are described. Nine patients (5%) developed hyperthyroidism 3 months after 131I treatment, and 5 patients (3%) developed radiation thyroiditis within the first month. Frozen sera were analyzed for thyroid peroxidase antibodies (anti-TPO) in 130 patients before 131I treatment. In 21% of these, serum levels of anti-TPO were over 200 U/mL. The complication frequency of Graves'-like hyperthyroidism and hypothyroidism was 51% in patients with elevated anti-TPO (n = 27) and 15% in patients with normal serum anti-TPO levels (P < 0.00005). TRAb, anti-TPO, and thyroglobulin were followed in patients developing hyperthyroidism or radiation thyroiditis and in 10 control patients remaining euthyroid. At the time of 131I treatment, all patients had serum TRAb values within the normal range. Three months after administration of 131I, the patients developing hyperthyroidism had a transient extensive rise in serum TRAb and anti-TPO levels parallel to a rise in the serum free T4 index. In patients developing radiation thyroiditis, serum TRAb values were normal. In control patients, serum TRAb and anti-TPO values were both within the normal range throughout the observation period. In conclusion, hyperthyroidism can be triggered by 131I in patients with nontoxic goiter, not only related to radiation thyroiditis but also as a Graves'-like hyperthyroidism induced by TRAb. Elevated anti-TPO pretreatment is a marker of an increased risk of side-effects to 131I treatment in nontoxic goiter.