Radioiodine Treatment Of Hyperthyroidism Research Articles

Can Radioiodine Treatment for Hyperthyroidism Cause Endothelial Dysfunction?

Can Radioiodine Treatment for Hyperthyroidism Cause Endothelial Dysfunction?

Outcome of Radioiodine Treatment in Hyperthyroidism and Predictive Factors of Treatment Failure: A 10-Year Experience

Objective: To analyze the effectiveness of the first dose of radioiodine (I-131) treatment in patients with hyperthyroidism in Southern Thailand. The second objective was to predict the factors implicated in treatment failure. Materials and Methods: Patients with hyperthyroidism who received first dose of I-131 between January 2010 and December 2019 at Songklanagarind Hospital were enrolled in the present retrospective study. The data collected included age, gender, duration of the disease, type of disease, thyroid gland size (by palpation), type of antithyroid drug (ATD), ATD dose, and time of withholding ATD before and after I-131 treatment. The effectiveness of the first dose of I-131 treatment was assessed after six months of treatment. Treatment success was defined as a euthyroid or hypothyroid status. Results: One thousand four hundred twenty-four patients with hyperthyroidism at a median age of 44.5 years and including 73.2% women were included in this study. Graves’ disease was the most common cause at 95.8%. The median I-131 dose was 7 mCi. Six months after treatment, 703 patients or 49.4%, achieved treatment success, which increased to 859 patients (60.3%) after 12 months. The authors found three factors that influenced treatment failure, duration of disease of seven months or longer (p=0.001), thyroid gland size of 100 g or larger (p=0.004), and I-131 treatment dose 10 to 19 mCi (p=0.021). The patient cohort was divided into three groups based on thyroid gland size at less than 50 g, 50 to 99 g, and more than 100 g, the I-131 treatment dose that increased the success rate of treatment in each group was 5 mCi or more, 6 mCi or more, and 15 mCi or more, respectively. Conclusion: A single dose of I-131 could successfully treat hyperthyroidism. The duration of the disease, size of the thyroid gland, and the dose of I-131 treatment had a substantial impact on the result. Thus, the authors recommended early treatment with I-131 at a suitable dose for patients with hyperthyroidism. Keywords: Radioiodine treatment; I-131; Hyperthyroidism; First dose

Radioiodine treatment of hyperthyroidism in cats: results of 165 cats treated by an individualised dosing algorithm in Spain.

Although radioiodine (131I) is the treatment of choice for feline hyperthyroidism, 131I-dosing protocols commonly induce iatrogenic hypothyroidism and expose azotaemia. A recently reported patient-specific 131I dosing algorithm minimised the risk of 131I-induced hypothyroidism and azotaemia, while maintaining high cure rates. The aim of the study was to report results of 131I treatment in a European population of hyperthyroid cats using this patient-specific dosing algorithm. This prospective case series (before-and-after study) evaluated 165 hyperthyroid cats referred for 131I treatment. All cats had serum concentrations of thyroxine (T4), triiodothyronine (T3) and thyroid-stimulating hormone (TSH) measured (off methimazole ⩾1 week). Thyroid volume and percentage uptake of 99mTc-pertechnetate (TcTU) were determined using thyroid scintigraphy. An initial 131I dose was calculated by averaging dose scores for T4/T3 concentrations, thyroid volume and TcTU; 70% of that composite dose was then administered. Twenty-four hours later, percentage 131I uptake was measured, and additional 131I administered as needed to deliver an adequate radiation dose to the thyroid tumour(s). Serum concentrations of T4, TSH and creatinine were determined 6-12 months later. Median calculated 131I dose was 2.15 mCi (range 1.2-7.5), with only 51 (30.9%) receiving ⩾2.5 mCi. Of 165 cats, 124 (75.2%) became euthyroid, seven (4.2%) became overtly hypothyroid, 27 (16.4%) became subclinically hypothyroid and seven (4.2%) remained hyperthyroid. A higher proportion of overtly (85.7%) and subclinically (26.9%) hypothyroid cats developed azotaemia than euthyroid cats (13.6%; P = 0.0002). Hypothyroid cats were older (P = 0.016) and more likely to have detectable TSH concentrations (P = 0.025) and symmetrical bilateral distribution of 99mTc-pertechnetate uptake (P = 0.0002), whereas persistently hyperthyroid cats had higher severity scores (P = 0.012). Our results confirm that 131I dosing with this new algorithm results in high cure rates, with a lowered prevalence of 131I-induced overt hypothyroidism and azotaemia. Age, serum TSH concentrations, bilateral, symmetrical uptake and severity score help predict outcome.

Development of hypothyroidism over 13 years of follow-up of patients with hyperthyroidism after radioiodine therapy.

To analyze the incidence and associated factors of hypothyroidism after radioiodine treatment for hyperthyroidism during a 13-year follow-up period. This was a retrospective study of consecutive patients with hyperthyroidism who were treated using a single dose of radioactive iodine (RAI) with a calculated dose regimen from 07/2005 to 12/2012. Univariate and multivariate Cox regression models were used to examine the factors that are associated with the occurrence of hypothyroidism after RAI therapy. Kaplan-Meier analysis was used for confirming associations between these models. A total of 182 patients were included during a 7.5-year median follow-up (range: 6-13 years). They were 36.4±11.1 years. The mean radioactive iodine dosage was 308.2±104.3 (range: 129.5-740.0) MBq. The rates of euthyroidism, early hypothyroidism, improvement, and ineffective treatment at 6 months were 48.4%, 37.9%, 8.8%, and 4.9%, respectively. The cumulative incidence of hypothyroidism in all patients with hyperthyroidism was 45.6% at 1 year, 48.9% at 5 years, and 52.3% at 10 years. Thyroid weight >46g (HR=0.643, 95%CI: 0.422-0.981, P=0.040) and a course of disease of 0.5-3 years (HR=0.592, 95%CI: 0.358-0.981, P=0.042) were identified as independent factors associated with an increased risk of hypothyroidism after radioactive iodine therapy. Radioactive iodine treatment with a calculated dose has a high cure rate for hyperthyroidism and has a low annual increase of hypothyroidism. Hypothyroidism after radioactive iodine treatment is more likely to occur in patients with small thyroid and a short disease course.

Radio-iodine treatment for thyrotoxicosis in unsuspected pregnancy

Radio-iodine treatment for thyrotoxicosis in unsuspected pregnancy

Radioiodine treatment for thyrotoxicosis in a district hospital: a re-audit

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Radioiodine therapy in benign thyroid disorders. Evaluation of French nuclear medicine practices

ObjectivesRadioiodine is currently used routinely in the treatment of hyperthyroidism including Graves’ disease (GD), toxic multinodular goitre (TMNG) and toxic solitary nodule (TSN) but no consensus exists on the most appropriate way to prescribe iodine – fixed dose or calculated doses based on the gland size or turnover of 131I. We carried out the first nationwide French survey assessing the current practices in radioiodine treatment of hyperthyroidism. Material and methodsA questionnaire was sent to French nuclear medicine hospital units and cancer treatment centres (n=69) about their practices in 2012. ResultsEuthyroidism was considered the successful outcome for 33% of respondents, whereas hypothyroidism was the aim in 26% of cases. Fixed activities were the commonest therapeutic approach (60.0% of GD prescribed doses and 72.5% for TMNG and TSN), followed by calculated activities from Marinelli's formula (based on a single uptake value and thyroid volume). The fixed administered dose was chosen from between 1 to 3 levels of standard doses, depending on the patient characteristics. Factors influencing this choice were disease, with a median of 370 MBq for GD and 555 MBq for TSN and TMNG, thyroid volume (59%) and uptake (52%) with 131I or 99mTc. Even physicians using fixed doses performed pretherapeutic thyroid scan (98%). ConclusionThis study shows that practices concerning the prescription of 131I therapeutic doses are heterogeneous. But the current trend in France, as in Europe, is the administration of fixed doses. The study provides the baseline data for exploring the evolution of French clinical practices.

Graves' Ophthalmopathy: Epidemiology and Natural History

Graves' ophthalmopathy (GO) is an autoimmune disorder of the orbit that is clinically relevant in 25-50% of patients with Graves' disease and 2% of patients with chronic thyroiditis. The age-adjusted annual incidence of clinically relevant GO is 16 per 100,000 population in women and 2.9 in men. At the onset of ophthalmopathy, 80-90% of patients have hyperthyroidism, with the rest having euthyroidism or hypothyroidism. The natural history of GO consists of two phases: an active inflammatory phase and a static phase. Anti-inflammatory therapy is indicated for the first phase of GO. Approximately 5% of patients experience late reactivation of GO. Asians appear to have less severe manifestations, with milder orbital edema, proptosis and muscle restriction. Genetic, anatomic and environmental factors influence the development of GO. Aging, thyroid dysfunction, thyroid stimulating hormone (TSH) receptor antibodies, smoking and radioiodine treatment for hyperthyroidism also influence the development and course of GO.

Long Term Efficacy of Radioiodine Treatment in Hyperthyroidism

Radioiodine is the mainstay of the treatment of thyroid hyperfunction. However, it is difficult to apply the appropriate amount of radioidone to achieve optimal efficacy with the least possible adverse effects. Results of the investigation on the efficacy of a relatively new protocol for radioiodine treatment of hyperthyroidism are reported. A retrospective evaluation of data from 326 patients with a mean average follow-up of 5.7 (1.0-11.7) years was performed. 64% of these patients suffered from Graves' disease and 36% had uni- or multinodular toxic goitre. In Graves' disease, the recurrence rate was 5% 1 year after the treatment, and that remained the same after 5 years. In toxic goitre, these rates were 6 and 7%, respectively. After 5 years 70% of the patients with autonomous adenomas were euthyroid, while 78% of the Graves patients developed hypothyroidism and 17% showed euthyroid state. A relationship between the lack of normalisation of thyroid-stimulating hormone levels after radioiodine treatment and the increased recurrence of late hyperthyroidism has also been established in patients with Graves's disease. Compared to the available data published in the literature, the success rate of the treatment is fairly high confirming the effectiveness of our protocol.

Erratum to: Changes in conjunctival cytology and tear function tests with radioiodine treatment for hyperthyroidism

Erratum to: Changes in conjunctival cytology and tear function tests with radioiodine treatment for hyperthyroidism

Radioiodine treatment of hyperthyroidism in the elderly

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Changes in conjunctival cytology and tear function tests with radioiodine treatment for hyperthyroidism

Radioiodine (RAI) is used in the treatment of hyperthyroidism and differentiated thyroid cancer. Radioiodine therapy is associated with dry eyes and some side effects are seen especially due to beta rays. In this study, the functional and cytological status of lacrimal glands after RAI therapy was evaluated. Twenty-five patients with a mean age of 55.16 years with planned low-dose RAI therapy were evaluated. Just before and 6 months after the treatment, the lacrimal glands were evaluated with tear break-up time (BUT), Schirmer's test, impression cytology and "Ocular Surface Disease Index (OSDI)" questionnaire. The mean value of Schirmer's test was 16.20 ± 3.61 pre-treatment and 11.28 ± 4.39 post-treatment for the right eye, and 15.76 ± 3.27 and 10.60 ± 4.42 for the left eye, respectively. The mean value of Schirmer's test decreased significantly post-treatment in both eyes (p = 0.0001). The BUT score also decreased significantly post-treatment (p = 0.001). The mean value of OSDI score was 27.5 ± 8.02 pre-treatment and 46.36 ± 10.27 post-treatment. The mean value of OSDI score increased post-treatment (p = 0.0001). The impression scores also increased post-treatment in both eyes (p = 0.0001). Even low-dose (≤30 mci) RAI treatment affects lacrimal gland functions. Low-dose RAI causes a decrease in the value of Schirmer's test and the BUT test, and an increase in the value of OSDI score and impression scores.

In contrast to matrix metalloproteinases, serum adiponectin concentrations increase after radioiodine treatment of thyrotoxicosis

BackgroundMatrix metalloproteinases (MMPs), together with their tissue inhibitors (TIMPs), remodel extracellular matrix under physiological and pathological conditions and are implicated in pathogenesis of cardiovascular diseases, cancer and in chronic inflammation. We have endeavoured to assess whether concentrations of MMPs, TIMPs, and anti-inflammatory adiponectin are altered by pharmacological treatment of acute thyrotoxicosis or by radioiodine therapy (RIT).Material and methodsWe measured serum concentrations of MMP-2, MMP-9, TIMP-1, TIMP-2, and adiponectin, TSH, free T4 (FT4) and free T3 (FT3) in 15 patients (4 males), age (years) 51.8±15.3 (mean±SD) with hyperthyroidism treated with thiamazole (Group 1) and in 20 subjects (2 males), treated for thyrotoxicosis with radioiodine, age 52.3±12.4 (Group 2), where blood samples were taken before RIT, visit 1 (V1), seven days post RIT, visit 2 (V2), and two to three months post RIT, visit 3 (V3).ResultsIn Group 1 there was no significant change in concentrations of MMP-2, MMP-9, TIMP-1, TIMP-2 or adiponectin, despite a fall in FT4 and FT3 (8.74±4.79 pg/ml vs 3.54±2.40 pg/ml, for FT3, and 4.48 ±2.21 ng/ml vs 1.02±1.07 ng/ml, for FT4, p<0.001). In Group 2 RIT did not cause any acute change in serum MMP-2, MMP-9, TIMP-1 and TIMP-2 or adiponectin (V1 vs V2). However, there was a significant increase in serum adiponectin [from 15201±8860 ng/ml (V1) to 19373±8657 ng/ml (at V3), p<0.05], and TIMP-2 at V3 [from 129±45 ng/ml (V1) to 149±38 ng/ml (V3), p<0.01]. There was no significant change MMP-2, MMP-9 and TIMP-1 between V1 and V3. There was a decrease in FT4 and FT3 from 24.4±15.4 pmol/l (V1) to 14.7±10.6 pmol/l (V3), and from 10.0±5.65 (V1) to 6.1±4.8 pmol/l (V2), p<0.01, for FT4 and FT3, respectively.ConclusionsRadioiodine therapy of thyrotoxicosis does not alter serum MMP-2, MMP-9 or TIMP-1 concentrations either acutely or after about three months of observation. An increase in serum adiponectin might reflect favourable effects of radioiodine administration on cardiovascular risk factors, while an increase in TIMP-2 (principal MMP-2 inhibitor) might lead to a decrease in free MMP-2 concentrations.

Body composition changes after radioiodine treatment of hyperthyroidism

Body composition changes after radioiodine treatment of hyperthyroidism

A NTCP approach for estimating the outcome in radioiodine treatment of hyperthyroidism

Radioiodine has been in use for over 60 years as a treatment for hyperthyroidism. Major changes in clinical practice have led to accurate dosimetry capable of avoiding the risks of adverse effects and the optimization of the treatment. The aim of this study was to test the capability of a radiobiological model, based on normal tissue complication probability (NTCP), to predict the outcome after oral therapeutic 131I administration. Following dosimetric study, 79 patients underwent treatment for hyperthyroidism using radioiodine and then 67 had at least a one-year follow up. The delivered dose was calculated using the MIRD formula, taking into account the measured maximum uptake of administered iodine transferred to the thyroid, U0, and the effective clearance rate, Teff and target mass. The dose was converted to normalized total dose delivered at 2 Gy per fraction (NTD2). Furthermore, the method to take into account the reduction of the mass of the gland during radioiodine therapy was also applied. The clinical outcome and dosimetric parameters were analyzed in order to study the dose-response relationship for hypothyroidism. The TD50 and m parameters of the NTCP model approach were then estimated using the likelihood method. The TD50, expressed as NTD2, resulted in 60 Gy (95% C.I.: 45-75 Gy) and 96 Gy (95% C.I.: 86-109 Gy) for patients affected by Graves or autonomous/multinodular disease, respectively. This supports the clinical evidence that Graves' disease should be characterized by more radiosensitive cells compared to autonomous nodules. The m parameter for all patients was 0.27 (95% C.I.: 0.22-0.36). These parameters were compared with those reported in the literature for hypothyroidism induced after external beam radiotherapy. The NTCP model correctly predicted the clinical outcome after the therapeutic administration of radioiodine in our series.

Comment on long-term risk in radioiodine treatment of hyperthyroidism

Comment on long-term risk in radioiodine treatment of hyperthyroidism

Radioiodine treatment of hyperthyroidism: fixed or calculated doses; intelligent design or science?

Dear Sir, In the ongoing debate about the optimal treatment of hyperthyroidism with radioiodine, Sisson et al. advocate a dose strategy, which is supported only in part by the authors’ arguments [1]. The development of hypothyroidism after the elimination of hyperthyroidism, inevitable as it may be, does not per se necessitate the acceleration of this outcome. Even though death is an inevitable consequence of life, we strive to delay this outcome as long as we possibly can. The incidence of hypothyroidism is about 3–5% per annum; thus, if a euthyroid state can be achieved, it may be maintained for about 15 years on average. Normal thyroid function provides a physiologic hormonal balance, adaptive to changes in metabolic and psychological states. Euthyroidism has been defined as the preferred treatment outcome in the Dutch conjoint evidence-based guideline on thyroid disorders [2]. Patients suffering from a recurrence of hyperthyroidism after treatment are usually kept on anti-thyroid drug (ATD) medication until a definitive cure has been achieved. As with this approach, there is no prolongation of clinically overt hyperthyroidism and the associated risks are non-existent. As pointed out by Sisson et al., radiation safety issues are not always respected. Indeed, the as low as reasonably achievable (ALARA) principle must not be ignored, least of all when detrimental effects are the expressed goal of the radionuclide application. In the aforementioned guideline, the ALARA principle has in fact been recognised as the single most compelling argument for choosing ATD treatment rather than radioiodine as the primary therapy option for patients with Graves’ hyperthyroidism [2]. A vast majority of European and Japanese physicians are inclined to give the patient this chance to have a spontaneous remission, thereby avoiding lifelong treatment with thyroxine [3]. Apparently, not all physicians agree that ‘the disorder should be eliminated as soon as possible’ when this involves an increased likelihood of early hypothyroidism. When radioiodine is applied only to patients failing ATD treatment, the overall radiation burden from this modality is reduced by 30–50% (i.e. the cure rate after ATD treatment). ALARA applies to patients, workers and members of the society alike. It is not self-evident how the radioiodine treatment goal can be achieved with the lowest radiation burden to all involved. In one study with a fixed dose of 370 MBq, about two-thirds of all patients were over-treated [4]. In another randomised, prospective study comparing 60 and 90 Gy target doses, the mean cumulative dose to achieve euthyroidism was 337 MBq [5]. Effectively, any dose regimen will result in a number of patients receiving amounts of radioiodine exceeding the dose required to cure hyperthyroidism. However, with an individually calculated dose, the extra radiation burden caused by additional treatments should be weighed against the reduced number of hypothyroid outcomes. Sisson et al. address a number of variables with prognostic impact on the radioiodine therapy outcome. In their discourse, they do not stipulate what ‘adjustments for the effects of known factors’ could be made. In patients with Graves’ hyperthyroidism, the radioiodine dose–effect relationship is largely influenced by such factors as thyroid volume and radioiodine turnover rate [6, 7]. The recommendation by Sisson et al. to measure the thyroid volume and the radioiodine uptake concurs with the view of many physicians. Whereas the authors do mention the inferiority of thyroid volume measurement by palpation, the same should be said for the very popular scintigraphic method, which harbours a mean error of about 30% [8, 9]. Radioiodine uptake measurements are another pitfall, as they show large variations over time in patients with Graves’ hyperthyroidism [10]. Consequently, uptake values may not contribute to more accurate radioiodine treatment doses unless they are performed immediately before radioiodine treatment. Moreover, a single measurement does not provide information about the radioiodine turnover rate, which bears directly on the thyroid absorbed dose [7, 11], and thus has a strong influence on the incidence of hypothyroidism after radioiodine treatment [12]. The authors’ statement concerning the relative consistency of the effective half-life of radioiodine is debatable—at least for patients with Graves’ hyperthyroidism, in whom differences in disease activity produce great differences in thyroidal iodine metabolism [10]. Proposals to dismiss radioiodine treatment strategies aiming at euthyroidism are premature. Whereas a number of therapeutically prognostic variables have been identified over the years, few are actually being applied in clinical practice. The consequent application of this scientific evidence will increase the probability of cure and may help resolve an issue that has been elusive for over six decades.

Cardiovascular and Cancer Mortality after Radioiodine Treatment of Hyperthyroidism

Cardiovascular and Cancer Mortality after Radioiodine Treatment of Hyperthyroidism

Radioiodine treatment of hyperthyroidism: fixed or calculated doses; intelligent design or science?

Radioiodine treatment of hyperthyroidism: fixed or calculated doses; intelligent design or science?

Increased cancer incidence after radioiodine treatment for hyperthyroidism

Concerns remain about risk of cancer after radioactive iodine (RAI) treatment for hyperthyroidism, especially in organs that concentrate iodine. The objective was to assess the long-term cancer risk from RAI treatment for hyperthyroidism. A total of 2793 hyperthyroid patients treated with RAI at Tampere University Hospital between 1965 and 2002, and 2793 age- and sex-matched reference subjects were followed for an average of 10 years through the Finnish Cancer Registry. Cancer incidence among hyperthyroid patients treated with RAI was higher than in the population-based control group (118.9 vs 94.9 per 10,000 person-years, rate ratio [RR], 1.25; 95% confidence interval [CI]: 1.08-1.46). Furthermore, incidence of stomach (RR, 1.75, 95% CI: 1.00-3.14), kidney (RR, 2.32; 95% CI: 1.06-5.09), and breast (RR, 1.53; 95% CI: 1.07-2.19) cancer was increased among RAI-treated patients. The relative risk of cancer increased with higher RAI dose administered. The increase in cancer incidence was statistically significant in patients treated at the age of 50-59 (RR, 1.44; 95% CI: 1.05-1.97) or older than 70 years (RR, 1.39; 95% CI: 1.05-1.82). There was a 5-year latent period after the RAI treatment before the cancer incidence began to differ between the RAI-treated hyperthyroid patients and the control group. Cancer incidence, especially cancer of the stomach, kidney, and breast, was higher in patients treated with RAI for hyperthyroidism.