Long-term follow-up study of radioiodine treatment of hyperthyroidism

A retrospective study with long term follow-up of Graves' disease patients treated with low activities of 131Iodine

BACKGROUND

Previous studies have shown that application of relatively low 131I-Iodine activities can successfully be used to treat patients with Graves' disease (GD). We assessed treatment outcome in the long-term follow-up of our GD patients and influencing factors.

METHODS

We evaluated 521 GD patients in this retrospective clinical single-center study. In all patients we performed scintigraphy and thyroid uptake measurement after 4 and 24 hours using 10 MBq 123I and calculated administered activity using Marinellis' formula. Treatment was done according to national regulations. Minimal routine clinical evaluation of all patients was available after 6 weeks and after 3, 6 and 12 months. Success of treatment was defined as euthyroid state or hypothyroidism 6 months after therapy.

RESULTS

We usually applied relatively low 131I activities. Three hundred seven patients (58.9%) became hypothyroid within 21 years of follow-up. One hundred thirty-nine patients (26.7%) became euthyroid and stayed euthyroid until the end of follow-up. We found a plateau after 7 years of initial therapy with only a few patients becoming hypothyroid after that time and identified 75 patients (14.4%) with persistent hyperthyroidism or recurrence.

CONCLUSIONS

Treatment with relatively low 131I activities produce favorable responses as shown in previous works. We found a high proportion of patients with long-term euthyroid state. Application of low activities reduces radiation burden of patients and, depending on radiation protection legislation, may lead to shortened hospital stay and reduced costs. Therefore, we feel that application of higher activities to treat GD patients as recommended in several current guidelines should be reconsidered.

Concomitant lithium increases radioiodine uptake and absorbed doses per administered activity in graves' disease: comparison of conventional versus lithium-augmented radioiodine therapy

Background

Lithium inhibits iodine and thyroid hormone release from thyroid cells, possibly increasing radioiodine retention and anti-hyperthyroid efficacy when given adjunctively to radioiodine therapy (RAI) of Graves’ disease (GD). However, the literature contains limited dosimetric data regarding the influence of concomitant lithium in this setting.

Methods

We retrospectively compared dosimetric variables in patients undergoing RAI with/without adjunctive lithium (n = 52 each). We assessed two low-dose, short-duration oral lithium carbonate regimens, 450 mg/d (n = 22) or 900 mg/d (n = 30), for a mean of 4.7 ± 1.4 d starting upon RAI administration. Patients underwent diagnostic testing to measure thyroidal radioiodine uptake (RAIU) 24 h ± 2 h after ingesting up to 5 MBq radioiodine, receiving individualized RAI activities 24 h later. Using ≥3 RAIU daily measurements starting 24 h post-RAI, researchers were able to determine the effective radioiodine half-life and absorbed dose to the thyroid; we also calculated the absorbed dose per administered activity concentration within that organ. Rates of GD cure, defined as reaching euthyroidism or hypothyroidism post-RAI, were evaluated in patients with ~6 months or longer post-RAI follow-up.

Results

The lithium dosage subgroups had similar dosimetric values and thus are considered together. Lithium patients and controls had similar average “diagnostic” RAIU (51.1% ± 15.7% vs. 50.6% ± 13.8%, p = 0.820), but the former had significantly higher RAIU post-RAI (56.3% ± 13.5% vs. 49.1% ± 13.5%, p = 0.002), reflecting significantly greater change in the former (+16.2% ± 30.4% vs. -1.8% ± 16.1%, p = 0.001). Radioiodine effective half-life was non-significantly longer in lithium patients (5.43 ± 1.50 d vs. 5.08 ± 1.16 d, p = 0.192). The mean RAI administered activity was 27% less in lithium patients (677 ± 294 MBq vs. 930 ± 433 MBq, p = 0.001), but GD cure rates were similar (83% [39/47] vs. 82% [33/40], p = 0.954), possibly due to the significantly higher thyroid dose in the lithium patients, especially in thyroid gland with a volume ≤ 20 mL (1.04 ± 0.44 Gy/MBq vs. 0.76 ± 0.30 Gy/MBq, p = 0.020). Day 3 serum lithium concentrations were low (450 mg/d: 0.26 ± 0.12 mmol/L, 900 mg/d: 0.50 ± 0.18 mmol/L); no lithium toxicity was noted.

Conclusion

Lithium augmentation may increase the RAIU and thyroid absorbed dose, permitting potentially decreased RAI activities without sacrificing efficacy. Our observations should be confirmed in a prospective, randomized trial.

Quality of life and decision regret in patients with late-hypothyroidism after radioiodine treatment for Graves' disease

OBJECTIVE

Patients with Graves' disease often engage in shared decision-making to select an individualised treatment regimen from multiple options. Radioactive iodine (RAI) is one of the treatment choices for their condition, aims to improve quality of life and well-being. Likewise, dissatisfaction with treatment outcomes can result in decision regret. We employed validated questionnaires to assess the prospective quality of life, decision regret and relative factors involved in decision-making of patients with late hypothyroidism after RAI therapy.

METHODS

A questionnaire survey was conducted among patients in hypothyroidism status for more than 1 year after RAI therapy. Disease-specific and generic QoL were assessed using the short form of thyroid-related patient-reported outcome (ThyPRO-39) questionnaire. Patient satisfaction regarding their decision to undergo RAI was assessed using the Decision Regret Scale (DRS) and patients were asked about the importance of relative factors in decision-making.

RESULTS

Of 254 patients who responded to the survey, the mean age of patients was 45.3 years (range: 18-78 years) and the median time from RAI therapy to survey was 4 years (range: 1-30 years). Patients' median and mean DRS score were 34.4 and 38.8 (range: 0-100), respectively. A total of 100 (39.4%) patients express absent-to-mild regret (score: 0-25), 154 (60.6%) patients express moderate-to-severe regret (score: >25). The mean score of the absent-to-mild regret group were significantly higher than those of the moderate-to-severe regret group on most ThyPRO-39 scales. A statistically significant positive correlation was observed between DRS score and most ThyPRO-39 scale score. There was a significant positive association between higher DRS score and longer time intervals after RAI treatment, a brief duration of hyperthyroidism, and the significance of long-time outpatient follow-up. More decision regret was negatively associated Iodine-free diet, ineffectiveness of ATD, fear of surgery.

CONCLUSION

Impairment of quality of life was positively correlated with decision regret in patients with late-hypothyroidism after radioiodine therapy. Patients with insufficient information support before decision-making are more likely to have higher decision regret after treatment. Our findings suggest that health providers should fully communicate with patients and provide information support in multiple dimensions during the shared-decision-making process.

The EANM guideline on radioiodine therapy of benign thyroid disease

This document provides the new EANM guideline on radioiodine therapy of benign thyroid disease. Its aim is to guide nuclear medicine physicians, endocrinologists, and practitioners in the selection of patients for radioiodine therapy. Its recommendations on patients' preparation, empiric and dosimetric therapeutic approaches, applied radioiodine activity, radiation protection requirements, and patients follow-up after administration of radioiodine therapy are extensively discussed.

Long-term effects of radioiodine treatment on thyroid functions and ultrasonographic features in patients with toxic adenoma and toxic multinodular goitre

OBJECTIVE

This study aimed to investigate the long-term effect of radioiodine (RAI) treatment on thyroid functions and ultrasonographic changes in the thyroid gland and toxic nodules.

METHODS

Thyroid function tests and ultrasonography reports of patients diagnosed with toxic adenoma (TA) or toxic multinodular goitre (TMNG) between 2000 and 2021 were retrospectively analysed.

RESULTS

We included 100 patients whom thyroid function and ultrasonography results were obtained from our outpatient clinic before and at least 36 months post-RAI. At the end of the follow-up period, the mean thyroid volume reduction in patients with TA and TMNG was 56.6% ± 3.1% and 51.1% ± 6.7%, respectively; the mean volume decrease of all toxic nodules was 80.5% ± 1.9%. The volume of the thyroid and toxic nodules was significantly reduced up to 12 years (p < 0.01). Between 3 and 10 years after RAI therapy, the annual incidence of hypothyroidism was 2.0% and 1.5% in the TA and TMNG groups, respectively. Toxic nodules were more frequently solid and hypoechoic in post-RAI ultrasounds (p < 0.01).

CONCLUSIONS

The volume of thyroid gland and toxic nodules continuously decreases, as the risk of hypothyroidism increases up to 10 years after RAI treatment. After RAI treatment, patients should be followed up to check their thyroid functions. In post-RAI examinations, toxic nodules may show ultrasonographic features suspicious for malignancy. History taking should include previous RAI therapies and old scintigraphy scans should be evaluated to avoid unnecessary procedures and non-diagnostic biopsy results.

Total thyroidectomy is more cost-effective than radioactive iodine as an alternative to antithyroid medication for Graves' disease

BACKGROUND

Patients with Graves' disease treated with radioactive iodine report worse quality of life than those treated by thyroidectomy. However, radioactive iodine is often selected due to lower risk of complications and lower cost. The objective of this study was to estimate the cost-effectiveness of radioactive iodine versus total thyroidectomy for treatment of Graves' disease.

METHODS

A Markov decision-analytic model was created to simulate clinical outcomes and costs of medication-refractory Graves' disease treated with radioactive iodine or total thyroidectomy. Complication rates and utilities were derived from published data. Costs were extracted from national Medicare reimbursement rates. We conducted 1-way, 2-way, and probabilistic sensitivity analyses to identify factors that influence cost-effectiveness and reflect uncertainty in model parameters. The willingness-to-pay threshold was set at $100,000/quality-adjusted life-years.

RESULTS

Total thyroidectomy yielded 23.6 quality-adjusted life-years versus 20.9 quality-adjusted life-years for radioactive iodine. The incremental cost-effectiveness ratio was $2,982 per quality-adjusted life-years, indicating that surgery is highly cost-effective relative to radioactive iodine. Surgery was more cost effective than radioactive iodine in 88.2% of model simulations. Sensitivity analyses indicate that the model outcomes are driven predominantly by posttreatment quality of life, with contributing effects from rates of treatment complications and the impact of these complications on quality of life.

CONCLUSION

For patients with Graves' disease who either cannot tolerate or are refractory to antithyroid drugs, thyroidectomy is more cost-effective than radioactive iodine. Future research should validate reported differences in quality of life between these 2 treatment modalities.

Graves' Disease in Children: An Update

Graves' disease (GD) is the most common cause of hyperthyroidism in children. A common GD symptom is a goiter. The usual biochemical profile in children with GD is a decreased thyroid hormone stimulating hormone (TSH) level and high free thyroxine (FT4) and free triiodothyronine (FT3) concentrations. The presence of thyroid receptor antibodies (TRAb) is the most important specific immunological sign for diagnosing GD. The treatment choices for pediatric GD are anti-thyroid drugs (ATDs), radioiodine, and thyroidectomy, but the risks and benefits of each modality are different. Management recommendations include the first-line use of a prolonged course of ATDs for at least 3 years and potentially 5 years or more. Rituximab and Teprotumumab are new novel alternative medications for the treatment of adult patients with GD and Graves' orbitopathy respectively, but evidence of the efficacy and safety of these drugs in pediatric patients with GD is lacking.

TPO antibody status prior to first radioactive iodine therapy as a predictive parameter for hypothyroidism in Graves' disease

Objective

We investigated whether a positive thyroid peroxidase antibody (TPO Ab) status before radioactive iodine (RAI) therapy in patients with Graves' hyperthyroidism is a predictive factor for developing hypothyroidism post RAI.

Methods

We performed a retrospective study of patients with Graves' hyperthyroidism with known TPO Ab status, receiving the first administration of RAI. Patients from four thyroid outpatient centres in Belgium receiving their first RAI therapy between the years 2011 and 2019 were studied. Clinical, laboratory, imaging, and treatment data were recorded from medical charts. Hypothyroidism and cure (defined as combined hypo- and euthyroidism) were evaluated in period 1 (≥2 and ≤9 months, closest to 6 months post RAI) and period 2 (>9 months and ≤24 months post RAI, closest to 12 months post RAI).

Results

A total of 152 patients were included of which 105 (69%) were TPO Ab-positive. Compared to TPO Ab-negative patients, TPO Ab-positive patients were younger, had a larger thyroid gland, and had more previous episodes of hyperthyroidism. In period 1, 89% of the TPO Ab-positive group developed hypothyroidism and 72% in the TPO Ab-negative group (P = 0.007). In period 2, the observation was similar: 88% vs 72% (P = 0.019). In the multivariate logistic regression analysis, a positive TPO Ab status was associated with hypothyroidism in period 2 (adjusted OR: 4.78; 95% CI: 1.27-20.18; P = 0.024). In period 1, the aOR was 4.16 (95% CI: 1.0-18.83; P = 0.052).

Conclusion

A positive TPO Ab status in patients with Graves' hyperthyroidism receiving the first administration of RAI is associated with a higher risk of early hypothyroidism.

Cost-Effectiveness Analysis of Antithyroid Drug (Propylthiouracil) Compared to Radioactive Iodine for the Treatment of Graves’ Disease in Ethiopia

Background

Graves’ disease is an autoimmune disorder caused by stimulating antibodies. The peak incidence of Graves’ disease occurs among patients aged 30 to 60 years. Radioactive iodine (RAI) and antithyroid drug (ATD) have been well-established therapies for the treatment of Graves’ disease for several decades. However, there remain large variations in practice among physicians in the preferred modality and the method of administration.

Objective

To assess the cost-effectiveness of ATD (propylthiouracil) compared to RAI from a health care payer perspective in Ethiopia.

Methods

Markov model was constructed by using TreeAge software 2021 with different parameters, such as ATD, RAI, treatment failure, treatment success, hypothyroidism, and supplemental thyroxine to conduct a cost-effectiveness analysis. A hypothetical 40-year-old female patient with symptomatic Graves’ hyperthyroidism was simulated to estimate expected lifetime health outcomes, quality-adjusted life years (QALYs) and costs, discounted at 3%.

Results

RAI has lesser QALYs (14.19) and is less expensive (US$ 3583.22), while ATD has higher QALYs (16.54) and is more expensive (US$ 12531.68). The result showed that there was no dominant treatment option. The incremental cost-effectiveness ratio was US$ 3811.6 per QALY which was greater than one to three times the cost-effectiveness threshold of Ethiopia (US$ 783).

Conclusion

In this cost-effectiveness analysis, RAI was the preferred treatment strategy for Graves’ disease, since the cost needed to get one extra QALY through ATD was greater than one to three times the cost-effectiveness threshold of Ethiopia.

High-dose radiation exposure and hypothyroidism: aetiology, prevention and replacement therapy

Without any doubt, high dose radiation exposure can induce hypothyroidism. However, there are open questions related to the mechanisms of its induction, corresponding dose thresholds and possible countermeasures. Therefore, this review addresses the aetiology, prevention and therapy of radiation induced hypothyroidism. External beam radiotherapy with several 10 Gy to the head and neck region and radioiodine therapy with several 100 Gy thyroid absorbed dose can destroy the thyroid gland and can induce autoantibodies against thyroid tissue. According to recent literature, clinical hypothyroidism is observed at threshold doses of ∼10 Gy after external beam radiotherapy and of ∼50 Gy after radioiodine therapy, children being more sensitive than adults. In children and adolescents exposed by the Chernobyl accident with mean thyroid absorbed doses of 500-800 mGy, subclinical hypothyroidism has been detected in 3%-6% of the cases with significant correlation to thyroid absorbed doses above 2.5 Gy. In case of nuclear emergencies, iodine thyroid blocking (ITB) is the method of choice to keep thyroid absorbed doses low. Large doses of stable iodine affect two different steps of internalization of radioiodine (transport and organification); perchlorate affecting the transport only may be an alternative to iodine. Administered before radioiodine incorporation, the effect of 100 mg iodide or more is still about 90% after 1 days, 80% after 2 days, and 50% or less after 3 days. If administered (too) late after exposure to radioiodine, the theoretically expected protective effect of ITB is about 50% after 6 h, 25% after 12 h, and about 6% after 24 h. In case of repeated or continuous exposure, repeated administration of 50 mg of iodide daily is indicated. If radiation-induced hypothyroidism cannot be avoided, thyroid hormone replacement therapy with individualized dosing and regular monitoring in order to maintain thyroid-stimulating hormone levels within the normal range ensures normal life expectancy.

Predicting outcomes in hyperthyroid cats treated with radioiodine

BACKGROUND

Radioiodine (¹³¹ I) is the treatment of choice for cats with hyperthyroidism. After ¹³¹ I, however, euthyroidism is not always achieved, with 5% to 10% of cats remaining persistently hyperthyroid and 20% to 50% developing iatrogenic hypothyroidism.

OBJECTIVES

To identify pretreatment factors that may help predict persistent hyperthyroidism and iatrogenic hypothyroidism after treatment of cats using a novel ¹³¹ I dosing algorithm.

ANIMALS

One thousand and four hundred hyperthyroid cats treated with ¹³¹ I.

METHODS

Prospective, before-and-after study. Pretreatment predictors (clinical, laboratory, scintigraphic, ¹³¹ I dose, ¹³¹ I uptake measurements) of treatment failure or iatrogenic hypothyroidism were identified by multivariable logistic regression analysis.

RESULTS

Cats that developed iatrogenic hypothyroidism were more likely to be older (odds ratio [OR] = 1.10; 95% confidence interval [CI], 1.04-1.17; P = .001), female (OR = 2.04; 95% CI, 1.54-2.70; P < .001), have detectable serum thyroid-stimulating hormone (TSH) concentrations (OR = 4.19; 95% CI, 2.0-8.81; P < .001), have bilateral thyroid nodules (OR = 1.57; 95% CI, 1.19-2.08; P < .001), have homogeneous, bilateral distribution of ^99m Tc-pertechnetate uptake (OR = 2.93; 95% CI, 2.05-4.19; P < .001), have milder severity score (OR = 0.62; 95% CI, 0.49-0.79; P < .001), and have higher ¹³¹ I uptake (OR = 2.40; 95% CI, 1.75-3.28; P < .001). In contrast, cats remaining persistently hyperthyroid were more likely to be younger (OR = 0.81; 95% CI, 0.72-0.92; P < .001), have higher severity score (OR = 1.87; 95% CI, 1.51-2.31; P < .001), and have lower ¹³¹ I uptake (OR = 3.50; 95% CI, 1.8-6.80; P < .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Age, sex, serum TSH concentration, bilateral and homogeneous ^99m Tc-pertechnetate uptake on scintigraphy, severity score, and percent ¹³¹ I uptake are all factors that might help predict outcome of ¹³¹ I treatment in hyperthyroid cats. Cats with persistent hyperthyroidism had many predictive factors that directly contrasted those of cats that developed ¹³¹ I-induced hypothyroidism.

Meta-Analysis of Randomized Controlled Trials Comparing the Efficacy of Radioactive Iodine Monotherapy versus Radioactive Iodine Therapy and Adjunctive Lithium for the Treatment of Hyperthyroidism

Background: The objective of this article is to evaluate the outcomes in patients undergoing radioactive iodine (RAI) with adjunctive lithium (Li) therapy versus (vs.) RAI therapy alone for the treatment of hyperthyroidism.Methods: A systematic review of the literature was undertaken to analyze clinical trials comparing RAI with adjunctive Li therapy vs. RAI therapy alone for the treatment of hyperthyroidism.Results: Six randomized-controlled trials (RCT) involving 755 patients were analyzed. RAI with adjunctive Li was associated with a significantly higher cure rate for hyperthyroidism when compared to RAI alone. Furthermore, a significantly higher cure rate for hyperthyroidism at 12 months was achieved with RAI and adjunctive Li. Adjuvant Li with RAI for ≤ 7 days showed significantly higher cure rate compared to RAI alone, whereas > 7 days of adjuvant Li with RAI did not show any difference in cure rate compared to RAI alone. RAI with adjunctive Li was associated with a significantly higher cure rate for patients with Graves' disease compared to RAI alone. There was no significant difference between RAI with adjunctive Li and RAI alone for toxic nodular thyroid disorder (toxic nodule and toxic multinodular goiter) and thyroid volume >40 grams and ≤40 grams.Conclusions: RAI with adjunctive Li therapy demonstrated superiority over RAI therapy alone with regards to both curing hyperthyroidism and, reduced time till cure, with a limited side effect profile. A large multicenter RCT is required, and if this confirms the data from these smaller trials, then this could change current practice.

Clinical efficacy of fixed-dose radioactive iodine for the treatment of hyperthyroidism at a single centre: our experience

BACKGROUND

Iodine-131 is an effective treatment for thyrotoxicosis. In 2019, National Institute for Clinical Excellence guidelines (UK) suggested offering radioactive iodine as first-line definitive treatment for adults with Graves' disease, toxic nodular and multinodular goitre unless it is unsuitable or anti-thyroid drugs are likely to achieve remission. The aim of this study was to evaluate the clinical outcome 1 year after using fixed-dose Iodine-131 for hyperthyroidism and time (months) to response.

METHODS

Electronic patient records were studied retrospectively for all patients who were treated with radioiodine therapy for hyperthyroidism between July 2017 and March 2020 at a district general hospital in the UK. Response to radioiodine therapy was initially assessed at 6 weeks and then at 3, 6, and 12 months by a dedicated thyroid nurse-led virtual follow-up.

RESULTS

We identified 67 patients with a mean age of 55.9 years (range 18-84); 48 (72%) females, 19 (28%) males. Of these, 57 (85%) patients were cured at 12 months (93.7% in non-Graves', 82.3% in Graves' group). Gender, diagnosis and pre-treatment disease interval were not significantly associated with treatment success. Non-Graves' patients had a significantly shorter time to discharge than Graves' patients receiving Iodine-131 (8 versus 10.3 months, p = 0.0174).

CONCLUSION

The results of the present study demonstrate that a single fixed dose of Iodine-131 therapy is highly effective and comparable to outcomes from calculated dose therapy in literature. We propose the routine use of scoring system to calculate risk of relapse for all newly diagnosed hyperthyroid patients to tailor treatment modality.

Treatment failure in hyperthyroid cats after radioiodine (I-131) injection

Background

There is limited published information on the outcome for cats where total thyroxine concentration (TT4) remains elevated after treatment with radioactive iodine (RAI).

Objective

To determine the frequency of, and predictors for, subsequent treatment failure in cats for which TT4 remains elevated at hospital discharge, and to report clinical outcomes for cats requiring repeat treatment.

Animals

One hundred twenty‐one cats with TT4 ≥40 nmol/L after treatment with RAI (out of an original, treated study sample of 959 cats).

Methods

Retrospective study. Data regarding signalment, weight, TT4 concentration (before RAI treatment, at discharge, and percentage change), day of sampling, and I‐131 dose were acquired. Logistic regression was performed to evaluate predictors of treatment failure.

Results

In the 87 cats for which classification was possible, 35 (40%) became euthyroid without further treatment. All TT4 variables and weight normalized RAI dose were independently predictive of subsequent treatment failure. In multivariate analysis, TT4 concentration at discharge (P < .001) and weight normalized RAI dose (P = .04) remained in the final model. All 28 cats with TT4 concentration ≥150 nmol/L at discharge ultimately failed treatment, compared with 13/40 (32.5%) and 11/19 (57.9%) cats with TT4 concentrations of 40‐100 nmol/L and 100‐150 nmol/L, respectively. Of the 52 cats that failed treatment, 14 were subsequently managed medically, 12 underwent thyroidectomy (4 with carcinoma), 14 had repeat RAI treatment which was successful in 12/14 (86%) cats, and 13 had no further treatment.

Conclusions and Clinical Importance

Cats with TT4 >150 nmol/L at discharge after RAI might be candidates for immediate repeat treatment.

Is There Any Need for Adjusting 131I Activity for the Treatment of High Turnover Graves' Disease Compared to Normal Turnover Patients? Results from a Retrospective Cohort Study Validated by Propensity Score Analysis

Purpose

To compare ¹³¹I-therapy outcomes in high turnover and normal turnover Graves' disease patients and predict optimal first ¹³¹I activity for high turnover patients.

Methods

Retrospective cohort design (1:2) validated by propensity score analysis. Cohort 1, high turnover (2-h RAIU/24-h RAIU ≥ 1), n = 104, and cohort 2, normal turnover (ratio < 1), n = 208, patients were compared for post ¹³¹I outcome. The cure was defined as a combined euthyroid and stable hypothyroid state following ¹³¹I treatment. Logistic regression analysis was used for identifying prognostic factors. The propensity score was applied; 77 matched pairs (1:1 ratio) of high and normal turnover patients were selected as a validation set.

Results

First ¹³¹I cure rates of 28% in high turnover and 66% in normal turnover groups (p = 0.001) were noted. The therapy cycles (median, 2 vs. 1) and cumulative ¹³¹I activity (median, 15 vs. 7 mCi) were required to cure hyperthyroidism in cohort 1 and cohort 2, respectively. Age (> 44 years), higher grade of goitre, and 2-h RAIU (> 37%) were associated with ¹³¹I therapy failure. The high turnover patients needed a factor of 1.5-2 times more ¹³¹I activity to achieve a similar cure rate compared to the normal turnover patients. The first-dose cure rate was 31% vs. 60% by propensity score analysis (n = 154), no way different (28% vs.66%) from the whole group of 312 patients.

Conclusion

High turnover Graves' disease patients, if administered standard ¹³¹I activity, the outcomes shall be poor. To improve the success rate, ¹³¹I activity should be increased by 1.5 to 2 times in the high turnover patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13139-020-00674-3.

Radioiodine therapy of Graves' disease

Graves' disease (GD), the most common cause of hyperthyroidism, is an autoimmune disease directly caused by circulating autoantibodies that bind and activate the TSH receptor, inducing metabolic activation of the thyroid gland; this may be associated with important cardiac (atrial fibrillation) and ocular (ophthalmopathy) complications. Treating GD with real curative intent implies the full elimination of the functioning thyroid parenchyma using surgery or radioactive iodine therapy (RAI). RAI has been used in humans with hyperthyroidism since 1941, thanks to the pioneering work of a physician (Dr. Saul Hertz) and a physicist (Dr. Arthur Roberts). The rationale of RAI is based on the effect of radiation of ¹³¹I on target cells leading to DNA damage, both directly, through breakage of molecular bonds, and indirectly through the formation of free radicals. In particular, irradiation causes a broad spectrum of cellular damage due to the production of reactive oxygen species and lipid peroxidation of the plasma membrane. Thus, RAI-related cellular death takes place through both apoptosis and necrosis. The aim of this review was to summarize indications, efficacy, safety profile, and dosimetric aspects of RAI treatment in patients affected by GD.

Dosimetry-guided radioiodine therapy of hyperthyroidism: long-term experience and implications for guidelines

BACKGROUND

Long-term follow-up after radioactive iodine therapy (RIT) for Graves' disease and toxic thyroid autonomy is incompletely addressed by current guidelines. We retrospectively analyzed the clinical course of 1233 out of 1728 consecutive Graves' disease (n = 536) and thyroid autonomy (n = 1192) patients after dosimetry-guided RIT to optimize follow-up.

METHODS

Patients were referred between 1990 and 2018; follow-up was monitored according to available electronic registers with medical reports, including autopsies from 9 hospitals and 10 residential care homes.

RESULTS

In total, 495/1728 cases were censored because of incomplete 6-month follow-up data. The conversion rates to hypothyroidism in Graves' disease and different forms of thyroid autonomy can be deconvoluted into two follow-up periods: first year after RIT and afterward. The conversion rate in Graves' disease was significantly higher than that in all thyroid autonomy subgroups during the first year but almost identical afterwards. Thyroxine substitution started between 10 and 7900 days after RIT at thyroid stimulating hormone between 0.11 and 177 µU/ml.

CONCLUSIONS

We advise earlier (2-3 weeks) first follow-up checks after RIT in all Graves' disease patients and thyroid autonomy under antithyroid drugs (ATD) and re-checks every 2-4 weeks until conversion to hypothyroidism during the first year. The first check in thyroid autonomy without ATD should be after 3-4 weeks with re-checks every 4-6 weeks. After 1 year, both groups can be re-checked every 4-6 months over the next 5 years. The success rate of RIT in thyroid autonomyincreases with age but the history of RIT is rapidly lost during follow-up.

Weight Gain After Thyroidectomy: A Systematic Review and Meta-Analysis

CONTEXT

Weight gain is a major driver of dissatisfaction and decreased quality of life in patients with hypothyroidism. Data on the changes in body weight following thyroidectomy are conflicting.

OBJECTIVE

To perform a systematic review of the literature and a meta-analysis of weight changes following total thyroidectomy.

DATA SOURCES

Literature search on PubMed.

STUDY SELECTION

Studies in English published between September 1998 and May 2018 reporting post-thyroidectomy weight changes.

DATA EXTRACTION

Data were reviewed and compared by 3 investigators; discrepancies were resolved by consensus. Meta-analyses were performed using fixed and random effect models. Univariable and multivariable meta-regression models for weight change were implemented against study follow-up, gender, and age. Exploratory subgroup analyses were performed for indication for surgery.

DATA SYNTHESIS

Seventeen studies (3164 patients) with 23.8 ± 23.6 months follow-up were included. Severe heterogeneity across studies was observed. Using a random effect model, the estimated overall weight change was a gain of 2.13 kg, 95% confidence interval (CI; 0.95, 3.30). Age was negatively associated with weight change (β = -0.238, P < 0.001). In subgroup analyses, weight gain was more evident in patients undergoing thyroidectomy for hyperthyroidism: 5.19 kg, 95% CI (3.21, 7.17) vs goiter or malignancy 1.55 kg, 95% CI (0.82, 2.27) and 1.30 kg, 95% CI (0.45, 2.15), respectively.

CONCLUSIONS

Patients undergoing thyroidectomy experience possible mild weight gain, particularly younger individuals and those with hyperthyroidism as the indication for surgery. Prospective studies directed to assess the pathophysiology of weight gain post-thyroidectomy, and to test novel treatment modalities, are needed to better characterize post-thyroidectomy weight changes.

Hypothyroidism after radiation exposure: brief narrative review

The thyroid gland is among the organs at the greatest risk of cancer from ionizing radiation. Epidemiological evidence from survivors of radiation therapy, atomic bombing, and the Chernobyl reactor accident, clearly shows that radiation exposure in childhood can cause thyroid cancer and benign thyroid nodules. Radiation exposure also may induce hypothyroidism and autoimmune reactions against the thyroid, but these effects are less well-documented. The literature includes only a few, methodologically weak animal studies regarding genetic/molecular mechanisms underlying hypothyroidism and thyroid autoimmunity after radiation exposure. Rather, evidence about radiation-induced hypothyroidism and thyroid autoimmunity derives mainly from follow-up studies in patients treated with external beam radiotherapy (EBRT) or iodine-131, and from epidemiological studies in the atomic bombing or nuclear accident survivors. Historically, hypothyroidism after external irradiation of the thyroid in adulthood was considered not to develop below a 10-20 Gy dose threshold. Newer data suggest a 10 Gy threshold after EBRT. By contrast, data from patients after iodine-131 "internal radiation therapy" of Graves´ disease indicate that hypothyroidism rarely occurs below thyroid doses of 50 Gy. Studies in children affected by the Chernobyl accident indicate that the dose threshold for hypothyroidism may be considerably lower, 3-5 Gy, aligning with observations in A-bomb survivors exposed as children. The reasons for these dose differences in radiosensitivity are not fully understood. Other important questions about the development of hypothyroidism after radiation exposure e.g., in utero, about the interaction between autoimmunity and hypofunction, and about the different effects of internal and external irradiation still must be answered.

Long-term Effects of Radioiodine in Toxic Multinodular Goiter: Thyroid Volume, Function, and Autoimmunity

CONTEXT

Long-term studies evaluating the treatment of toxic multinodular goiter (TMNG) with fixed activities of radioiodine (RAI) are lacking.

OBJECTIVE

The objective of this work is to describe the effects of 15 mCi on thyroid volume, function, and autoimmunity in the long term.

DESIGN AND SETTING

A population-based, retrospective analysis with up to 12 years of follow-up was conducted in Siena, Italy.

PARTICIPANTS

Adult patients (n = 153) with TMNG, naive to RAI, were included.

METHODS

Evaluation was performed of thyroid function, antithyroid antibodies, and ultrasound scans before and yearly after RAI.

MAIN OUTCOME MEASURES

Evaluations included hyperthyroidism cure, hypothyroidism, volume reduction, nadir and regain, and antibody titer change.

RESULTS

The study revealed mean volume reductions greater than or equal to 50% at 3 years after RAI; the greatest annual reduction was observed during the first year (30 ± 17.8%; P < .001). Most patients (60%) achieved their volume nadir 3 to 6 years after RAI. Although 22% patients showed volume regain, the net reduction was statistically significant as late as 9 years after RAI (P = .005). The mean time to hypothyroidism was 2.7 ± 2.4 years, and it was associated with greater reductions in volume (P = .01). During the first 3 years after treatment, hyperthyroid patients decreased approximately by 50% per year without additional RAI. There was no statistically significant association of antibody titers with thyroid function except for antithyrotropin receptor antibodies and hyperthyroidism (P = .004). At the end of follow-up there were 61.6% euthyroid patients, 11% hyperthyroid (4.8% overt), and 27.4% hypothyroid patients (2.7% overt). Hyperthyroidism was cured in 89%.

CONCLUSIONS

The treatment of TMNG with 15 mCi of RAI induced low hypothyroidism rates while providing high cure rates and significant volume reduction, which was maintained in the long term.

Predictors of euthyreosis in hyperthyroid patients treated with radioiodine 131I-: a retrospective study

BACKGROUND

Radioiodine (RAI) treatment for hyperthyroidism is a very common modality, chosen by physicians worldwide. The outcome of the therapy, however, is not always predictable. While rendering a patient hypo- or euthyroid is meant as a therapeutic success, the latter does not require lifelong hormonal supplementation. The aim of our study is to determine predictors of euthyreosis in patients who underwent RAI treatment.

METHODS

Medical records of 144 patients who had undergone RAI therapy were examined. Laboratory and clinical data were analyzed statistically. Ultrasonography findings, such as thyroid volume, nodules' size and characteristics had been collected at the beginning of treatment and 6 months after the administration of radioiodine ¹³¹I^-. Moreover, scintigraphy results were taken into account. Multivariate logistic regression analysis model has been used to find predictors of euthyroidism after 12 months of follow-up. The predictors of normal thyroid function have also been analyzed separately for patients with GD (Graves' disease) and TMNG (toxic multinodular goiter).

RESULTS

The analysis showed that age (OR 1,06; 95%CI 1.025-1.096, p = 0,001), thyroid gland volume (OR 1,04; 95%CI 1,02-1,06; p < 0.001) and iodine uptake level (OR 0,952; 95%CI 0,91-0,98; p = 0,004) were significant factors of achieving normal thyroid function after RAI therapy. According to multivariate logistic regression analysis, in GD patients only age has been shown to be a significant factor (OR 1,06; 95%CI 1,001-1,13; p = 0.047), while in TMNG patients' age (OR 1,04; 95%CI 1-1,09; p = 0.048), thyroid gland volume (OR 1.038; 95%CI 1.009-1.068; p = 0.009) and iodine uptake level (OR 0.95; 95%CI 0.9-0.99; p = 0.02) all have been proven to be significant predictors of achieving euthyroidism.

CONCLUSIONS

The more advanced age, larger volume of thyroid gland and lower iodine uptake level are predictors of euthyreosis after RAI treatment.

Current controversies in the management of Graves' hyperthyroidism

Introduction: The management of Graves' disease centers on the use of effective and well-established therapies, namely thionamide antithyroid drugs, radioactive iodine, and thyroidectomy. Optimal treatment strategies are however controversial and vary significantly across centers.Areas covered: This review addresses specific controversies in Graves' disease management including the choice of primary therapy, the approach to women planning pregnancy, and optimal strategies for antithyroid drug and radioiodine therapy.Expert opinion: Important considerations in choosing therapy include treatment efficacy, adverse effects, patient convenience, and resource settings. Recent data suggest that early and effective control of hyperthyroidism is key to improving cardiovascular morbidity and mortality. Studies addressing cancer risk in radioiodine-treated patients face methodological challenges and require clarification in appropriately designed studies. Remission rates with antithyroid drugs are comparable when thionamides are used alone (titration-regimen) or in combination with levothyroxine (block and replace) and can be optimized by extending treatment for at least 12-18 months. Fixed and calculated radioiodine activity regimens are both effective but entail a trade-off between convenience and precision in the administered activity. Optimal preconception strategies are still evolving but ablative treatment in advance of pregnancy offers the most pragmatic means of reducing adverse effects of hyperthyroidism in subsequent pregnancy.

Long-term outcome and prognostic factors of single-dose Radioiodine Therapy in patients with Graves' disease

BACKGROUND/PURPOSE

Few studies exist investigating the effectiveness of radioiodine (RAI) therapy for hyperthyroidism patients in Asia. We herein investigated the real-world efficacy of single-dose RAI therapy in Taiwanese patients with Graves' disease (GD).

METHODS

This is a retrospective study of 243 patients with GD recorded between 1989 and 2016 in a tertiary referral hospital. Eu- or hypothyroid after RAI therapy were defined as the successful group. Kaplan-Meier curve and cox-regression model were used for analysis of prognostic factors.

RESULTS

Of the 243 patients, 187 were females, with mean age of 46.9 ± 13.6 years. Most patients (63.8%) did not choose RAI as the first-line therapy. The median dose was 7 mCi, with a mean follow-up period of 107.1 ± 82.8 months. The overall success rate was 70.9%. Univariate analysis revealed calculated- or fixed-dose (P = 0.015), goiter size (P < 0.001), and RAI dose (P = 0.022) were the factors affecting RAI effectiveness, multivariate analysis indicated goiter size was the independent factor. Patients with grade 0-2 goiter had a higher success rate than patients with grade 3 goiter (HR = 2.1, 95%CI = 1.34-3.27, P = 0.001), although the former were treated with lower RAI dose than the latter (7.8 ± 3.2 mCi vs 8.8 ± 3.3 mCi, P = 0.049). However, if the grade 3 goiters became smaller within 3 months of therapy, the success rate was not inferior to grade 0-2 goiter.

CONCLUSION

In Taiwan, RAI therapy for GD patients reached an overall success rate of 70.9%, with a median dose of 7 mCi. This study identified patients with grade 3 goiter need a more aggressive RAI regimen.

Serum Thyroid Hormone Balance in Levothyroxine Monotherapy-Treated Patients with Atrophic Thyroid After Radioiodine Treatment for Graves' Disease

Background: Some studies reported that among athyreotic patients on levothyroxine (LT4) after total thyroidectomy, patients with normal serum thyrotropin (TSH) levels had mildly low serum free triiodothyronine (fT3) levels, whereas patients with mildly suppressed serum TSH levels had normal serum fT3 levels. The reduction of the thyroid volume (TV) after radioiodine treatment for Graves' disease is well known; however, a few studies evaluated thyroidal function including serum triiodothyronine (T3) levels of hypothyroid patients on LT4 after radioiodine treatment in detail. Methods: We retrospectively studied 446 patients treated with LT4 for radioiodine-induced hypothyroidism and who had undergone ultrasonography. We compared serum fT4 and fT3 levels in hypothyroid patients on LT4 who presented an atrophic thyroid change after radioiodine treatment, with those in the euthyroid matched control group with intact thyroids. We also stratified patients with normal TSH levels according to TV and evaluated serum thyroid hormone levels. Results: In 356 of 446 (80%) patients, TV was lower than the lower limit of the 95% reference range of controls. Excluding 43 patients with high serum TSH levels, we assessed thyroid function test results in 313 patients with atrophic thyroid glands. Of these cases, eight patients with strongly suppressed TSH levels had serum fT3 levels that were significantly higher than those in controls (p < 0.001). Overall, 27 patients with mildly suppressed TSH levels had serum fT3 levels equivalent to those in controls (p = 0.386), whereas 278 patients with normal TSH levels had serum fT3 levels that were significantly lower than those in controls (p < 0.001). We also assessed fT3 levels relative to TV in 326 patients with normal TSH levels. Of these cases, in 267 patients with TV less than 5 mL and in 46 patients with TV between 5 and 10 mL, serum fT3 levels were significantly lower than those in controls (p < 0.001). In 13 patients with TV more than 10 mL, serum fT3 levels were equivalent to those in controls (p = 0.844). Conclusions: Serum thyroid hormone balance in most patients on LT4 after radioiodine treatment for Graves' disease was similar to that in athyreotic patients on LT4. Mild TSH suppression with LT4 is needed to achieve normal fT3 levels in such patients.

Characteristics and outcomes of patients with hyperthyroidism attending a hospital endocrine clinic-A retrospective study

AIMS

A study looking at the distribution, management and outcomes of patients referred to a secondary care endocrine clinic with a diagnosis of hyperthyroidism.

METHODS

Retrospective longitudinal study of 442 patients referred over a 15-year period (2002-2017) with a diagnosis of hyperthyroidism to a secondary care endocrine clinic. Information on demographics, diagnosis, treatments and outcomes was recorded as patients attended for clinic visits. Patients were initially treated with 1-2 courses of thionamides and subsequently referred for radioiodine or surgery in cases of relapse.

RESULTS

Patients (75% female, age range 17-91 years) were treated with thionamides for an average of 295 days. As expected, the majority of patients had Graves Disease (GD) (80%), followed by those with multinodular goitre (MNG) (8.6%), amiodarone-induced hyperthyroidism (6.7%) and toxic nodule (3.7%). Drug-induced remission rates were best seen in patients with GD (43%), and side effects necessitating change in treatment were relatively low (2.5%). In 121 patients who received radioiodine, hypothyroidism occurred in 50% of patients and was commoner in patients with GD (65%) than in those with MNG (22%) and toxic nodule (6.3%).

CONCLUSIONS

This study is only one of a few reporting on the characteristics of patients with hyperthyroidism attending a typical secondary care endocrine clinic. Whilst we appreciate its limitations, we encourage similar methods of collecting valuable real world data to facilitate conduction of specialist peer review visits in other similar clinic settings.

Radioiodine treatment for graves' disease: a 10-year Australian cohort study

BACKGROUND

Radioactive iodine (I131) is a common definitive treatment for Graves' Disease. Potential complications include worsening, or new development of Graves' eye disease and development of a radiation thyroiditis. The purpose of the present study was to assess outcomes of patients treated with I131 in an Australian tertiary centre over 10 years.

METHODS

Data from 101 consecutive patients treated with I131 for a diagnosis of Graves' disease between 2005 to 2015 was collected and reviewed retrospectively. Baseline TSH receptor antibody titre, pre-treatment free thyroxine (FT4), technetium scan uptake, initial treatment, duration of treatment, reason for definitive therapy, complications, and time to remission (defined as euthyroidism or hypothyroidism after 12 months) were recorded.

RESULTS

Of the 92 patients with adequate outcome data, 73 (79.3%) patients achieved remission with a single dose of I131. Of the remaining 19 patients, 12 had a second dose and became hypothyroid. TSH receptor antibody titre at diagnosis was significantly lower in the group that achieved remission with the first dose compared with those who did not (P = 0.0071). There was no difference in technetium uptake, I131 dose, duration of therapy or pre-treatment free thyroxine (FT4). I131 was complicated by development of eye disease in 3 patients and 1 (of 11 with pre-existing eye disease) had worsening eye disease. A clinically apparent flare of hyperthyroidism following I131 was evident in 8 patients (8.6%).

CONCLUSION

Radioiodine is an effective therapy for Graves' Disease with few complications. The majority of patients achieve remission with a single dose. Those who require a second dose are more likely to have higher TSH receptor antibody titres at diagnosis. To the best of our knowledge, this is the first study to report outcomes from radioiodine treatment for Graves' disease in an Australian population.

Dosimetry-based treatment for Graves' disease

Objective

The aim of this retrospective study was to assess the long-term outcome of a personalized dosimetry approach in Graves’ disease aiming to render patients euthyroid from a planned thyroid absorbed dose of 60 Gy.

Patients and methods

A total of 284 patients with Graves’ disease were followed prospectively following administration of radioiodine calculated to deliver an absorbed dose of 60 Gy. Patients with cardiac disease were excluded. Outcomes were analysed at yearly intervals for up to 10 years with a median follow-up of 37.5 months.

Results

A single radioiodine administration was sufficient to render a patient either euthyroid or hypothyroid in 175 (62%) patients, the remainder requiring further radioiodine. The median radioactivity required to deliver 60 Gy was 77 MBq. Less than 2% patients required 400–600 MBq, the standard activity administered in many centres. In the cohort receiving a single administration, 38, 32 and 26% were euthyroid on no specific thyroid medication at 3, 5 and 10 years, respectively. Larger thyroid volumes were associated with the need for further therapy. The presence of nodules on ultrasonography did not adversely affect treatment outcome.

Conclusion

A personalized dosimetric approach delayed the long-term onset of hypothyroidism in 26% of patients. This was achieved using much lower administered activities than currently recommended. Future studies will aim to identify those patients who would benefit most from this approach.

Hypothyroidism and its associated factors after radioactive iodine therapy among patients with hyperthyroidism in the Northeast Coast State of Malaysia

Objectives

The aim of this study was to determine the incidence of hypothyroidism and its associated factors within one-year post radioactive iodine (RAI) therapy.

Methods

A retrospective study was conducted among patients with hyperthyroidism who received RAI therapy at Nuclear Medicine Clinic, Hospital Universiti Sains Malaysia (HUSM), Kelantan. Data regarding patients’ demographics, gender, aetiology of hyperthyroidism, presence of autoantibodies, dose of RAI used and usage of antithyroid drug post RAI therapy were included in the analysis.

Results

Of a total of 167 screened patients, 137 subjects were eligible for this study. The incidence of hypothyroidism within one year of RAI therapy was 32.9%. Women were found to be less likely to develop hypothyroidism post RAI therapy (adjusted odds ratio, 0.406; 95% confidence interval: 0.181–0.908; p = 0.028). The usage of antithyroid drug post RAI was significantly associated with a lower incidence of hypothyroidism post RAI therapy (adjusted odds ratio, 0.188; 95% confidence interval: 0.081–0.438; p<0.001).

Conclusion

This study showed a high incidence of hypothyroidism within one-year post RAI therapy. Gender and usage of antithyroid drug post RAI therapy are significantly associated with the development of hypothyroidism.

Prognostic factor analysis in 325 patients with Graves' disease treated with radioiodine therapy

Introduction

¹³¹I therapy is a choice for Graves’ hyperthyroidism. Several factors that affect the success of ¹³¹I treatment in Graves’ disease (GD) patients have been put forward. The aim of this retrospective study was to evaluate the factors influencing the success of ¹³¹I therapy and the occurrence of hypothyroidism after ¹³¹I therapy.

Patients and methods

We reviewed 325 GD patients, who were well documented out of 779 cases, treated with ¹³¹I in the First Affiliated Hospital of Xi’an Jiaotong University between 2010 and 2016. We collected the potential influencing factors, including demographic data (age, sex, family history), iodine intake state, antithyroid drugs (ATD) taking, thyroid texture, complications of hyperthyroidism, physical and laboratory examinations [thyroid weight, effective ¹³¹I half-life time (T_eff), 24-h iodine uptake rate, tri-iodothyronine, thyroxine, free tri-iodothyronine (FT3), free thyroxine, thyroid-stimulating hormone, thyroglobulin antibody, thyroid microsome antibody, thyrotropin receptor antibody], and final administered dosages according to Quimby formula. The correlations between the prognosis of GD patients and these factors were analyzed by logistic regression analysis.

Results

Out of 325 patients, 247 (76.00%) were treated successfully with radioiodine. GD patients who were cured by ¹³¹I therapy were more likely to have smaller thyroid [odds ratio (OR)=0.988, 95% confidence interval (CI)=0.980–0.996, P=0.002], lower FT4 levels (OR=0.993, 95% CI=0.988–0.997, P=0.002), and shorter time of ATD withdrawal before ¹³¹I treatment (OR=0.985, 95% CI=0.975–0.996, P=0.002). Hypothyroidism occurred in 132 (41.00%) out of 325 patients. There was an increased risk of early hypothyroidism in patients with lower 24-h iodine uptake (OR=0.964, 95% CI=0.941–0.988, P=0.004), and treated with a lower total dose of iodine (OR=0.892, 95% CI=0.824–0.965, P=0.005) and a higher iodine dose per garm of thyroid tissue (OR=5.414E+14, 95% CI=45.495–6.444E+27, P=0.027).

Conclusion

Our results showed that ¹³¹I treatment was more successful in patients with lower weight of the thyroid, lower free thyroxine level, and shorter ATD taking period. Furthermore, early hypothyroidism after radioiodine treatment was more likely to occur in patients with lower 24-h iodine uptake, lower total dose of iodine, and higher iodine dose per garm of thyroid tissue.

Radiation-related thyroid autoimmunity and dysfunction

The thyroid gland is vulnerable not only to external radiation but also to internal radiation, because the thyroid cells can incorporate radioactive iodine when synthesizing thyroid hormones. Since radiation-induction of thyroid neoplasia, including thyroid cancer, is well recognized, the data on radiation-related thyroid autoimmunity and dysfunction are summarized and reviewed. High-dose irradiation, irrespective of being external or internal, is strongly associated with a risk of hypothyroidism (with the prevalence ranging from 2.4% to 31%) and of Graves' hyperthyroidism (with the prevalence being up to 5%). It is easy to understand that high-dose irradiation induces hypothyroidism with some frequency, because high-dose irradiation destroys the thyroid gland. On the other hand, the basis for development of hyperthyroidism is mechanistically unclear, and it is merely speculative that autoantigens may be released from damaged thyroid glands and recognized by the immune system, leading to the development of anti-thyrotropin receptor antibodies and Graves' hyperthyroidism in subjects who are immunologically predisposed to this ailment. In contrast, the data on moderate to low-dose irradiation on thyroid autoimmunity and dysfunction are inconsistent. Although it is difficult to draw a definitive conclusion, some data may suggest a transient effect of moderate- to low-dose irradiation on hypothyroidism and autoimmune thyroiditis, implying that the effect, if it exists, is reversible. Finally, no report has shown a statistically significant increase in the prevalence of moderate- to low-dose irradiation-induced Graves' hyperthyroidism.

Single-Session High-Intensity Focused Ultrasound Treatment for Persistent or Relapsed Graves Disease: Preliminary Experience in a Prospective Study

Purpose To evaluate the safety and efficacy of ultrasonography (US)-guided high-intensity focused ultrasound (HIFU) ablation as a treatment for medically refractory Graves disease (GD). Materials and Methods After ethics approval, a prospective trial (NCT02685514) was performed from November 2015 to February 2016. Thirty patients underwent ablation of the entire right and left thyroid lobes, with areas near the tracheal-esophageal groove and common carotid artery left unablated. Serum thyroid-stimulating hormone (TSH), free T4 (FT4), antithyroid autoantibodies, and TSH receptor (TSHR) antibody levels were evaluated afterward, and US color Doppler, US volumetry, and eye assessment were performed. The primary outcome was the 12-month relapse rate. Relapse referred to hyperthyroidism (FT4 > 23 pmol/L) afterward. Variables associated with relapse were analyzed by using binary logistic regression. Results The technical success rate was 96.7%. The cohort comprised entirely women, with a median age of 38.2 years (interquartile range, 29.5-49.0 years). After 12 months, eight patients (26.7%; 95% confidence interval [CI]: 14.19%, 44.95%) experienced relapse. One patient (3.3%; 95% CI: 0.59%, 16.67%) experienced vocal cord palsy, while two patients (6.7%; 95% CI: 1.85%, 21.33%) experienced Horner syndrome, but none of these conditions were permanent. No changes in gland volume, antithyroid autoantibody levels, and ophthalmic parameters were found at 12-month follow-up. Baseline TSHR was found to have decreased significantly at 6- and 12-month follow-up (P < .001 for both). TSHR antibody (odds ratio [OR] = 1.414; 95% CI: 1.018, 1.965; P = .039) and gland volume (OR = 0.557; 95% CI: 0.353, 0.880; P = .012) were associated with 12-month relapse, with higher antibody levels conferring a higher likelihood and smaller gland volumes conferring a lower likelihood. Conclusion US-guided HIFU of the thyroid may be a safe and efficacious treatment in patients with persistent or relapsed GD. However, further study is warranted before it can become mainstream for this indication. ^© RSNA, 2017 Online supplemental material is available for this article.

Effect of Antithyroid Therapies on Bone and Body Composition: A Prospective, Randomized, Clinical Study Comparing Antithyroid Drugs with Radioiodine Therapy

BACKGROUND

Thyrotoxicosis is associated with loss of body weight and bone mineral content (BMC). Antithyroid drugs (ATD) and radioiodine therapy (RIT) are the common options for the management of thyrotoxicosis. We evaluated the effect of ATD and RIT on BMC and body composition.

MATERIALS AND METHODS

In this prospective study, we randomized 60 patients of thyrotoxicosis (20-50 years, treatment naïve, males) to receive either ATD (Group 1) using carbimazole or RIT (Group 2). We excluded patients with significant ophthalmopathy and thyroid malignancy. The patients were followed serially for 1 year. Body composition was analyzed using the bioimpedance method and BMC by dual-energy X-ray absorptiometry technique. The data were analyzed using appropriate statistical measures.

RESULTS

The patients had a mean age of 33 ± 4.2 years and mean symptoms duration of 8.2 ± 2.7 months before the diagnosis. A total of 51 patients had Graves' disease, and the remaining 9 had toxic multinodular goiter. BMC at lumbar spine and femoral neck improved with both the therapies similarly at the end of 1 year. The body weight, protein, and fat content also increased after 1 year of observation similar between the two groups. None of the observed parameters showed a difference with regard to the mode of ATD.

CONCLUSION

ATD and RIT have comparable effects on the bone and body composition in the management of thyrotoxicosis. Further long-term studies are needed to confirm the observed findings.

Study of factors that influence the outcome of 131I treatment in hyperthyroidism secondary to nodular goitre

OBJECTIVE

To assess the outcome after ¹³¹I treatment in patients with multinodular (MNG) and nodular toxic goitre (NTG) according to the administered dose and other factors related to the patient, pathology, or previous treatments.

MATERIAL AND METHODS

A retrospective study was conducted on 108 patients (67 MNG and 41 NTG) treated in our department, with a follow-up period of at least 2 years. Development of hypothyroidism and treatment failure were evaluated along with their relationship with the administered dose and other factors such as age, sex, grade of hyperthyroidism, type of goitre, presence of autoimmunity, or previous antithyroid medication.

RESULTS

More than one-third (36.9%) of MNG patients, and even higher proportion of NTG patients (51.2%) developed non-transient hypothyroidism, particularly in those receiving 740MBq (66.7%). No relationship was found with any other variable. The development of early hypothyroidism (before one year) was also not related to any variable. Treatment failure was not related to the dose, but in MNG there was a relationship with male gender, presence of autoimmunity, or previous antithyroid drugs use.

CONCLUSIONS

The high rate of hypothyroidism obtained with high doses of ¹³¹I in hyperthyroidism secondary to nodular goitre treatment suggests that lower doses might be sufficient to control the disease without an increase in treatment failures. Only patients with positive autoimmunity, in previous anti-thyroid medication, and perhaps male gender in MNG might be given higher doses, as the failure rate increases, but further studies are required.

DYNAMIC CHANGES OF TRAb AND TPOAb AFTER RADIOIODINE THERAPY IN GRAVES' DISEASE

Context

To analyze the dynamic changes of serum thyrotrophin receptor antibody (TRAb) and thyroid peroxidase antibody (TPOAb) in Graves' disease (GD) patients before and after radioactive iodine (RAI) treatment and to investigate if TRAb and TPOAb play a role in the occurrence of early hypothyroidism after ¹³¹I therapy for Graves' hyperthyroidism.

Subjects and Methods

A total of 240 patients newly diagnosed with GD were selected to study. A clinical and laboratory assessment was performed before and at 3, 6, and 12 months after ¹³¹I therapy. Chemiluminescent immunoassays were used to detect serum free triiodothyronine (FT3), free thyroxine (FT4), sensitive thyroid-stimulating hormone (TSH) and TPOAb concentration. Radio-receptor assay was used to measure serum TRAb concentration. According to the early onset of hypothyroidism in a year after RAI therapy, patients were divided into early hypothyroidism group (group A) and non-early hypothyroidism group (group B).

Results

In both groups, serum TRAb and TPOAb increased at 3 months, reached the highest level at 6 months and returned to the baseline at 12 months after RAI therapy. TRAb showed a significant difference between the two groups at 6 months (P<0.01). Serum TPOAb in group A was higher than that in group B before and at 3, 6, 12 months after RAI therapy (P<0.05).

Conclusions

Serum TRAb and TPOAb are closely related to the occurrence of the early hypothyroidism, and play an important role in judging prognosis after ¹³¹I treatment in Graves' disease.

Cost-utility analysis comparing radioactive iodine, anti-thyroid drugs and total thyroidectomy for primary treatment of Graves' disease

OBJECTIVE

Little data is in existence about the most cost-effective primary treatment for Graves' disease. We performed a cost-utility analysis comparing radioactive iodine (RAI), anti-thyroid drugs (ATD) and total thyroidectomy (TT) as first-line therapy for Graves' disease in England and Australia.

METHODS

We used a Markov model to compare lifetime costs and benefits (quality-adjusted life-years (QALYs)). The model included efficacy, rates of relapse and major complications associated with each treatment, and alternative second-line therapies. Model parameters were obtained from published literature. One-way sensitivity analyses were conducted. Costs were presented in 2015£ or Australian Dollars (AUD).

RESULTS

RAI was the least expensive therapy in both England (£5425; QALYs 34.73) and Australia (AUD5601; 30.97 QALYs). In base case results, in both countries, ATD was a cost-effective alternative to RAI (£16 866; 35.17 QALYs; incremental cost-effectiveness ratio (ICER) £26 279 per QALY gained England; AUD8924; 31.37 QALYs; ICER AUD9687 per QALY gained Australia), while RAI dominated TT (£7115; QALYs 33.93 England; AUD15 668; 30.25 QALYs Australia). In sensitivity analysis, base case results were stable to changes in most cost, transition probabilities and health-relative quality-of-life (HRQoL) weights; however, in England, the results were sensitive to changes in the HRQoL weights of hypothyroidism and euthyroidism on ATD.

CONCLUSIONS

In this analysis, RAI is the least expensive choice for first-line treatment strategy for Graves' disease. In England and Australia, ATD is likely to be a cost-effective alternative, while TT is unlikely to be cost-effective. Further research into HRQoL in Graves' disease could improve the quality of future studies.

Follow-up and evaluation of the pregnancy outcome in women of reproductive age with Graves' disease after 131Iodine treatment

The aims of the present study were to analyze the outcomes of pregnancy, after ¹³¹I treatment, in patients of reproductive age with Graves' hyperthyroidism and to investigate the effects, if any, of the ¹³¹I treatment on the mothers and newborns. From 2009 to 2014, 257 pregnant female patients with Graves' hyperthyroidism in the outpatients at the Department of Nuclear Medicine and 166 healthy pregnant women from the Department of Obstetrics at Sun Yat-Sen Memorial Hospital were included in our study. They were divided into a ¹³¹I therapy group (n = 130) and an anti-thyroid drug (ATD) group (n = 127) according to their therapy before conception. The neonatal gender, rate of preterm birth, body weight ratio and occurrence of low birth weight [except for higher rates of abortion (odds ratio; OR = 2.023) and cesarean delivery (OR = 1.552) in patients with Graves' hyperthyroidism] showed no statistically significant differences from those of the healthy group (P > 0.05). The level of intrauterine growth restriction did not differ between the Graves' hyperthyroidism group and the healthy group (8 vs 2, 3.0% vs 1.2%). The outcomes of pregnancy among the ¹³¹I therapy group, ATD group and healthy group also showed no significant differences. Of the patients treated with ¹³¹I, no significant differences were observed in the outcomes of their pregnancies, whether they received propylthiouracil (PTU), levothyroxine or no additional drug treatment during pregnancy. Women with hyperthyroidism who were treated with ¹³¹I therapy could have normal delivery if they ceased ¹³¹I treatment for at least six months prior to conception and if their thyroid function was reasonably controlled and maintained using the medication: anti-thyroid drug and levothyroxine before and during pregnancy.

Long-Term Results of Fixed High-Dose I-131 Treatment for Toxic Nodular Goiter: Higher Euthyroidism Rates in Geriatric Patients

Objective:

Geriatric patient population has special importance due to particular challenges. In addition to the increase in incidence of toxic nodular goiter (TNG) with age, it has a high incidence in the regions of low-medium iodine intake such as in our country. The aim of this study was to evaluate the overall outcome of high fixed dose radioiodine (RAI) therapy, and investigate the particular differences in the geriatric patient population.

Methods:

One hundred and three TNG patients treated with high dose I-131 (370-740 MBq) were retrospectively reviewed. The baseline characteristics; age, gender, scintigraphic patterns and thyroid function tests before and after treatment, as well as follow-up, duration of antithyroid drug (ATD) medication and achievement of euthyroid or hypothyroid state were evaluated. The patient population was divided into two groups as those=>65 years and those who were younger, in order to assess the effect of age.

Results:

Treatment success was 90% with single dose RAI therapy. Hyperthyroidism was treated in 7±7, 2 months after RAI administration. At the end of the first year, overall hypothyroidism rate was 30% and euthyroid state was achieved in 70% of patients. Age was found to be the only statistically significant variable effecting outcome. A higher ratio of euthyroidism was achieved in the geriatric patient population.

Conclusion:

High fixed dose I-131 treatment should be preferred in geriatric TNG patients in order to treat persistent hyperthyroidism rapidly. The result of this study suggests that high fixed dose RAI therapy is a successful modality in treating TNG, and high rates of euthyroidism can be achieved in geriatric patients.

Response to Radioiodine Therapy for Thyrotoxicosis: Disparate Outcomes for an Indigenous Population

Despite 70 years of experience treating thyrotoxic patients with radioiodine not all patients are successfully treated by a single dose. Multiple factors predicting radioiodine efficacy have been reported. The aim of this study was to assess whether ethnicity was associated with radioiodine response. A retrospective review was performed of patients who received radioiodine therapy for thyrotoxicosis from 1 January 2008 to 31 December 2010 and had follow-up available of a minimum of 12 months. 224 patients were included, 82.4% female, and 63.7% had Graves's disease. Radioiodine failed in 21.5% of patients overall, with a higher failure rate in the indigenous population (35.2%). When controlling for other influencing factors by logistic regression, there continued to be an increased risk for the indigenous group (OR 2.82) and those treated with antithyroid drugs following radioiodine (OR 2.04). Younger age was also associated with an increased risk of failing radioiodine therapy (OR 0.97 for each year of age). Cure rates following radioiodine were lower for indigenes independent of factors known to affect radioiodine outcome. This is the first report demonstrating ethnicity as a possible independent variable for radioiodine efficacy. Further work is needed to investigate the cause of this difference.

The Sonographic Features of the Thyroid Gland After Treatment with Radioiodine Therapy in Patients with Graves' Disease

The aim of the study was to describe the typical sonographic features of the thyroid gland in patients with Graves' hyperthyroidism after radioiodine therapy (RIT). Thirty patients (21 female and 9 male) with a mean age of 53 y (standard deviation [SD] ± 11.3) and with previous Graves' disease who had been successfully treated with RIT were enrolled in the study. All were hypothyroid or euthyroid after treatment. The thyroid ultrasound was carried out by a single experienced operator with an 8-MHz linear transducer. Volume, vascularity, echogenicity and echotexture of the glands were noted. The presence of nodules and lymph nodes was also documented. The mean volumes of the right lobe were 2.4 mL ± 2.9 SD (0.6-14) and the left lobe were 1.8 mL ± 1.9 SD (0.4-9.1), with a mean total volume of 4.2 mL ± 4.7 SD (1.3-19.1). Of those who had a pre-treatment ultrasound (23%), the percentage reduction in volume was 87% (p < 0.05); 93% of the glands were hypovascular, with the remaining 7% showing normal vascularity. The glands were hyperechoic and of coarse echotexture. Overall, the sonographic features of the post-RIT gland included a significantly reduced mean total volume of 4.2 mL, hypovascularity, coarse echotexture and hyperechogenicity.

Effectiveness of Radioiodine Treatment for Toxic Nodular Goiter

OBJECTIVE

The aim of this retrospective study is to evaluate the treatment outcomes in patients with toxic nodular goiter (TNG) that received radioiodine treatment (RAIT) and to determine the influence of age, gender, nodule size, I-131 dose, underlying etiology and antithyroid drugs on the outcomes of RAIT.

METHODS

Two hundred thirty three patients (mean 64±10 years old) with TNG that received RAIT were included in the study. Treatment success was analyzed according to demographic (age and gender) and clinical data (thyroid function tests before and after RAIT, thyroid sonography and scintigraphy, I-131 dose, antithyroid drugs). A fixed dose of 555 MBq was administered to patients with nodules smaller than 2 cm in diameter and of 740 MBq to patients with nodules larger than 2 cm. Hyperthyroidism treatment success was defined as achieving hypothyroidism or euthyroidism six months after RAIT.

RESULTS

In our study, the cure rate was 93.9% six months after RAIT. Hypothyroidism was observed in 74 (31.7%) patients, and euthyroidism was achieved in 145 (62.2%) patients while 14 (6%) patients remained in hyperthyroid state. Age and gender did not affect treatment outcomes. No correlation was found between underlying etiology or antithyroid drugs and therapeutic effectiveness. The effectiveness of RAIT was better in patients with nodules smaller than 2 cm.

CONCLUSION

We observed that high cure rates were obtained in patients with TNG with 555 MBq and 740 MBq doses of I-131. While nodule diameter and RAI dose are important factors for treatment efficacy; age, gender, underlying etiology and antithyroid drugs do not affect the outcome of RAIT.

Long-term carbimazole pretreatment reduces the efficacy of radioiodine therapy

INTRODUCTION

Data from several studies suggest that pretreatment with antithyroid drugs (ATD) before (131)I increases the risk of treatment failure. This effect has been demonstrated more consistently with propylthiouracil than with carbimazole (CMZ) or methimazole (MMI). Men with Graves' disease (GD) have a lower rate of remission with (131)I compared to women and the impact of long-term ATD pretreatment on the success of (131)I is unknown. The objective of our study was to compare the efficacy of fixed doses of radioiodine between patients with and without long-term CMZ pretreatment.

MATERIALS AND METHODS

We performed a retrospective study on 335 male patients with GD treated with (131)I from 1998 to 2008. 148 patients had been pretreated with CMZ, and the remaining 187 patients received (131)I without pretreatment. We compared the success rate of a single dose of (131)I, between patients with and without long-term CMZ pretreatment.

RESULTS

The success rate of a single dose of (131)I was significantly higher in patients without pretreatment than in patients who were pretreated with CMZ (91.4% vs. 82.3%, P = 0.01). The rate of hypothyroidism in the first 6 months after (131)I therapy was significantly higher in patients without pretreatment (55.1% vs. 44.6%, P = 0.05). There was also a trend for higher cumulative rate of hypothyroidism at last follow-up in nonpretreated patients (78.1% vs. 69.7%).

CONCLUSION

Male patients with Graves' hyperthyroidism pretreated with CMZ have lower efficacy with 131I therapy compared to nonpretreated patients. CMZ pretreatment given for a prolonged period reduces the efficacy of (131)I therapy.

Radioiodine treatment of Graves' disease - dose/response analysis

The clinical outcome of 153 Graves' disease patients treated with a wide dose range of radioactive iodine-131 (RAI) was analyzed retrospectively. Six to nine months after the first dose of RAI 60 patients (39%) were hypothyroid (or rather thyroxine-substituted) and 26 (17%) were euthyroid, while 67 patients (44%) did not respond properly: in 32 (21%) their antithyroid drug (ATD) dose could be reduced but not withdrawn (partial response) and 35 (23%) remained hyperthyroid or the same dose of ATD was necessary (no response). The outcome did not correspond significantly to the administered activity of RAI (medians 259, 259, 222, and 259 MBq for hypothyroid, euthyroid, partial, and no response subgroups, respectively), or the activity retained in the gland at 24 h (medians 127, 105, 143, and 152 MBq). The effect was, however, clearly, and in a stepwise pattern, dependent on initial thyroid volume (17, 26, 33 and 35 ml, P < 0.001) or activity per gram tissue retained at 24 h (6.02, 4.95, 4.75, and 4.44 MBq/g, P = 0.002). Also, higher residual level of thyrotoxicosis at the time of RAI treatment was connected with worse outcome. The dose-dependency of outcome was further analyzed. When our sample was divided into tertiles, according to the adjusted dose, the same modest success rates (47%) were seen in the lower and middle tertiles. However, doses higher than 5.88 MBq/g (the upper tertile) resulted in success rate of 75%. Finer division into decils has shown a threshold-like increase in cure rate between the 7th and the 8th decil. In the first 7 decils (doses ≤ 6 MBq/g) the complete response rate was 45 to 50%, in the 8th decil (6.0 to 7.8~MBq/g) it rose to 80% and was not further increased with increasing dose. Direct comparison of higher (> 6 MBq/g, cure rate 80%) and lower (≤ 6 MBq/g, cure rate 46%) doses gave highly significant difference (P < 0.001). With our dosing range we found a dose-dependent clinical outcome that suggests an optimum delivered dose near 6.5 MBq/g, resulting in successful treatment of ca 80% patients.

The role of radioiodine therapy in benign nodular goitre

For treatment of benign nodular goitre the choice usually stands between surgery and (131)I therapy. (131)I therapy, used for 30 years for this condition, leads to a goitre volume reduction of 35-50% within 1-2 years. However, this treatment has limited efficacy if the thyroid (131)I uptake is low or if the goitre is large. Recombinant human TSH (rhTSH)-stimulated (131)I therapy significantly improves goitre reduction, as compared with conventional (131)I therapy without pre-stimulation, and adverse effects are few with rhTSH doses of 0.1 mg or lower. RhTSH-stimulated (131)I therapy reduces the need for additional therapy due to insufficient goitre reduction, but the price is a higher rate of hypothyroidism. Another approach with rhTSH-stimulation is to reduce the administered (131)I activity by a factor that equals the increase in the thyroid (131)I uptake. Using this approach, radiation exposure is considerably reduced while the goitre reduction is similar to that obtained with conventional (131)I therapy.