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

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67 patients (44%) did not respond properly: in 32 (21%) their antithyroid drug (ATD) dose could be reduced but not withdrawn (partial response) and 35 (23%) remained hyperthyroid or the same dose of ATD was necessary (no response).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.

Failure of radioactive iodine in the treatment of hyperthyroidism

BACKGROUND

Persistent or recurrent hyperthyroidism after treatment with radioactive iodine (RAI) is common and many patients require either additional doses or surgery before they are cured. The purpose of this study was to identify patterns and predictors of failure of RAI in patients with hyperthyroidism.

METHODS

We conducted a retrospective review of patients treated with RAI from 2007 to 2010. Failure of RAI was defined as receipt of additional dose(s) and/or total thyroidectomy. Using a Cox proportional hazards model, we conducted univariate analysis to identify factors associated with failure of RAI. A final multivariate model was then constructed with significant (p < 0.05) variables from the univariate analysis.

RESULTS

Of the 325 patients analyzed, 74 patients (22.8 %) failed initial RAI treatment, 53 (71.6 %) received additional RAI, 13 (17.6 %) received additional RAI followed by surgery, and the remaining 8 (10.8 %) were cured after thyroidectomy. The percentage of patients who failed decreased in a stepwise fashion as RAI dose increased. Similarly, the incidence of failure increased as the presenting T3 level increased. Sensitivity analysis revealed that RAI doses <12.5 mCi were associated with failure while initial T3 and free T4 levels of at least 4.5 pg/mL and 2.3 ng/dL, respectively, were associated with failure. In the final multivariate analysis, higher T4 (hazard ratio [HR] 1.13; 95 % confidence interval [CI] 1.02-1.26; p = 0.02) and methimazole treatment (HR 2.55; 95 % CI 1.22-5.33; p = 0.01) were associated with failure.

CONCLUSIONS

Laboratory values at presentation can predict which patients with hyperthyroidism are at risk for failing RAI treatment. Higher doses of RAI or surgical referral may prevent the need for repeat RAI in selected patients.

Treatment with thyroid hormone

Thyroid hormone deficiency can have important repercussions. Treatment with thyroid hormone in replacement doses is essential in patients with hypothyroidism. In this review, we critically discuss the thyroid hormone formulations that are available and approaches to correct replacement therapy with thyroid hormone in primary and central hypothyroidism in different periods of life such as pregnancy, birth, infancy, childhood, and adolescence as well as in adult patients, the elderly, and in patients with comorbidities. Despite the frequent and long term use of l-T4, several studies have documented frequent under- and overtreatment during replacement therapy in hypothyroid patients. We assess the factors determining l-T4 requirements (sex, age, gender, menstrual status, body weight, and lean body mass), the major causes of failure to achieve optimal serum TSH levels in undertreated patients (poor patient compliance, timing of l-T4 administration, interferences with absorption, gastrointestinal diseases, and drugs), and the adverse consequences of unintentional TSH suppression in overtreated patients. Opinions differ regarding the treatment of mild thyroid hormone deficiency, and we examine the recent evidence favoring treatment of this condition. New data suggesting that combined therapy with T3 and T4 could be indicated in some patients with hypothyroidism are assessed, and the indications for TSH suppression with l-T4 in patients with euthyroid multinodular goiter and in those with differentiated thyroid cancer are reviewed. Lastly, we address the potential use of thyroid hormones or their analogs in obese patients and in severe cardiac diseases, dyslipidemia, and nonthyroidal illnesses.

Evaluating the efficacy of primary treatment for graves' disease complicated by thyrotoxic periodic paralysis

Objective. Thyrotoxic periodic paralysis (TPP) is a potentially life-threatening complication of Graves' disease (GD). The present study compared the long-term efficacy of antithyroid drugs (ATD), radioactive iodine (RAI), and surgery in GD/TPP. Methods. Sixteen patients with GD/TPP were followed over a 14-year period. ATD was generally prescribed upfront for 12-18 months before RAI or surgery was considered. Outcomes such as thyrotoxic or TPP relapses were compared between the three modalities. Results. Eight (50.0%) patients had ATD alone, 4 (25.0%) had RAI, and 4 (25.0%) had surgery as primary treatment. Despite being able to withdraw ATD in all 8 patients for 37.5 (22-247) months, all subsequently developed thyrotoxic relapses and 4 (50.0%) had ≥1 TPP relapses. Of the four patients who had RAI, two (50%) developed thyrotoxic relapse after 12 and 29 months, respectively, and two (50.0%) became hypothyroid. The median required RAI dose to render hypothyroidism was 550 (350-700) MBq. Of the 4 patients who underwent surgery, none developed relapses but all became hypothyroid. Conclusion. To minimize future relapses, more definitive primary treatment such as RAI or surgery is preferred over ATD alone. If RAI is chosen over surgery, a higher dose (>550 MBq) is recommended.

Predictors of treatment failure, incipient hypothyroidism, and weight gain following radioiodine therapy for Graves' thyrotoxicosis

BACKGROUND

Following radioiodine ((131)I) therapy, both late recognition of hypothyroidism and treatment failure may result in adverse outcomes.

AIM

We sought to assess indicators of both incipient hypothyroidism and treatment failure following (131)I and determine factors predictive of weight gain.

SUBJECTS AND METHODS

Retrospective study of 288 patients receiving (131)I for treatment of Graves' thyrotoxicosis. Primary outcome measures were thyroid status and weight change at 1 yr following (131)I.

RESULTS

The treatment failure rate at 1 yr was 13.5%. Hypothyroidism developed in 80.9%, with 58.5% of patients having levels of free T4 (fT4) <6 pmol/l at diagnosis. Patients receiving thionamides before and after (131)I had significantly higher levels of treatment failure (23.3%) than those with no thionamide exposure (6.3%, p=0.003), but also had more active Graves' disease. Following (131)I, development of a detectable TSH or low-normal fT4 levels was not associated with recurrent thyrotoxicosis. Median weight gain was 5.3 kg, although patients with nadir fT4 levels <6 pmol/l gained an average 2 kg more than those with levels >6 pmol/l (p=0.05). The main predictor of weight gain was fT4 level immediately prior to treatment; those in the lowest tertile gained a median 3.1 kg whilst those in the highest tertile gained 7.4 kg (median difference 4.3 kg; 95% confidence interval: 2.5-6.2).

CONCLUSIONS

Marked hypothyroidism following (131)I is common and often occurs early. Simple biochemical parameters may help identify incipient hypothyroidism and potentially limit excess weight gain. Treatment failure is common in patients with severe thyrotoxicosis and in such cases larger doses of (131)I may be warranted.

Total thyroidectomy for safe and definitive management of Graves' disease

Background:

The role of total thyroidectomy in the management of patients with Graves' disease remains controversial. However, there is increasing evidence to support the role of the procedure as a safe and definitive treatment for Graves' disease.

Method:

Patients were identified from a prospective thyroid database of the multidisciplinary thyroid clinic at Hull Royal Infirmary. All case notes were independently reviewed to confirm the data held on the database.

Results:

Over a 7-year period, the senior author has performed 206 total thyroidectomies for Graves' disease. The incidence of temporary recurrent laryngeal nerve palsy and hypoparathyroidism was 3.4 per cent and 24 per cent respectively. There was one case of permanent unilateral recurrent laryngeal nerve palsy, and 3.9 per cent of patients developed permanent hypoparathyroidism. There has been no relapse of thyrotoxicosis.

Conclusion:

In the context of a multidisciplinary thyroid clinic, total thyroidectomy should be offered as a safe and effective first-line treatment option for Graves' disease.

Radioiodine therapy in benign thyroid diseases: effects, side effects, and factors affecting therapeutic outcome

Radioiodine ((131)I) therapy of benign thyroid diseases was introduced 70 yr ago, and the patients treated since then are probably numbered in the millions. Fifty to 90% of hyperthyroid patients are cured within 1 yr after (131)I therapy. With longer follow-up, permanent hypothyroidism seems inevitable in Graves' disease, whereas this risk is much lower when treating toxic nodular goiter. The side effect causing most concern is the potential induction of ophthalmopathy in predisposed individuals. The response to (131)I therapy is to some extent related to the radiation dose. However, calculation of an exact thyroid dose is error-prone due to imprecise measurement of the (131)I biokinetics, and the importance of internal dosimetric factors, such as the thyroid follicle size, is probably underestimated. Besides these obstacles, several potential confounders interfere with the efficacy of (131)I therapy, and they may even interact mutually and counteract each other. Numerous studies have evaluated the effect of (131)I therapy, but results have been conflicting due to differences in design, sample size, patient selection, and dose calculation. It seems clear that no single factor reliably predicts the outcome from (131)I therapy. The individual radiosensitivity, still poorly defined and impossible to quantify, may be a major determinant of the outcome from (131)I therapy. Above all, the impact of (131)I therapy relies on the iodine-concentrating ability of the thyroid gland. The thyroid (131)I uptake (or retention) can be stimulated in several ways, including dietary iodine restriction and use of lithium. In particular, recombinant human thyrotropin has gained interest because this compound significantly amplifies the effect of (131)I therapy in patients with nontoxic nodular goiter.

Evidence for higher success rates and successful treatment earlier in Graves' disease with higher radioactive iodine doses

BACKGROUND

Graves' disease is commonly treated with curative intent using radioactive iodine (RAI). While higher doses have been shown to increase success rates, more evidence is needed. Further, very few studies assess the time to treatment success without the need for antithyroid drugs after a single dose of RAI within the first year post-dose, despite earlier success being an important treatment objective. We aimed to evaluate the outcome of different RAI doses in terms of success rates and time to achieve this success (eu- or hypothyroidism). We hypothesized that higher doses would not only increase success rates, but bring about successful treatment earlier.

METHODS

We retrospectively analyzed the medical records of all patients diagnosed with Graves' disease between 1994 and 2009. Details of RAI treatment and outcomes thereof were documented. In our analysis, we divided the patients who received RAI treatment into three groups according to the dose received: I (≤15 mCi); II (16-20 mCi); III (≥21 mCi).

RESULTS

There were 498 patients diagnosed with Graves' disease. However, 105 were either lost to follow-up or still undergoing treatment. Of the remaining 393, there were 258 who received RAI treatment. The average initial dose was 21.42±6.5 mCi and overall success rate was 86%. Success rates were 74%, 85%, and 89% (p<0.05), while average time to successful treatment was 8.1, 4.6, and 2.9 months, respectively (p<0.001), for groups I, II, and III. When 20 mCi was given empirically, 85% obtained successful treatment; most of these within 3 months (mean 3.9; mode and median 3 months).

CONCLUSIONS

This study provides additional evidence that success post-treatment correlates with administered dose and shows clearly, for the first time, that successful treatment is achieved earlier with higher doses. This knowledge is relevant to all clinicians managing Graves' disease as it can be taken into consideration when discussing treatment plans with patients.

Adjuvant lithium improves the efficacy of radioactive iodine treatment in Graves' and toxic nodular disease

CONTEXT

Lithium increases iodine retention in the thyroid gland and inhibits thyroid hormone release. Although lithium has been reported to improve the efficacy of radioactive iodine (RAI) treatment in Graves' disease, its role as an adjunct to RAI treatment of hyperthyroidism, particularly in toxic nodular disease, remains contentious.

OBJECTIVE

To assess whether adjuvant lithium increases the efficacy of a fixed dose RAI regimen in Graves' and toxic nodular hyperthyroid patients.

DESIGN AND SETTING

Retrospective cohort study in a tertiary referral centre. Two hundred and four hyperthyroid patients (163 Graves' disease, 26 toxic multinodular goitre and 15 solitary toxic thyroid adenoma).

INTERVENTION

One hundred and three patients received RAI alone (median dose 558 MBq). One hundred and one patients received RAI (median dose 571 MBq) with adjuvant lithium (800 mg/day for 10 days).

MAIN OUTCOME MEASURE

Proportion of patients cured at any time over a 1-year period following RAI treatment. Cure was defined as sustained (two or more sequential time points) biochemical euthyroidism or hypothyroidism during the follow-up period.

RESULTS

The likelihood of cure at any time was 60% greater in all hyperthyroid patients (Graves' plus toxic nodular disease) receiving adjuvant lithium (n = 204, P = 0·003). In patients with Graves' disease receiving RAI + lithium, there was a similar occurrence in cure (n = 163, P = 0·006). Cure was twice as likely in patients with toxic nodular (non-Graves') disease receiving RAI + lithium compared with RAI alone (n = 41, P = 0·01).

CONCLUSIONS

This study supports the use of adjuvant lithium to improve the efficacy of RAI in the treatment of Grave's disease and suggests a novel role in the management of toxic nodular (non-Graves') disease.

What is the best definitive treatment for Graves' disease? A systematic review of the existing literature

BACKGROUND

The management guidelines of the American Thyroid Association and American Association of Clinical Endocrinologists for Graves' disease (GD) include any of the following modalities: (131)I therapy, antithyroid medication, or thyroidectomy. No in-depth analysis has been performed comparing the treatment options, even though a single treatment option seems to be universally accepted.

METHODS

A systematic review of the literature was performed to examine contemporary literature between 2001 and 2011 evaluating the management options of GD. We compiled retrospective and prospective studies analyzing surgery and radioactive iodine. Outcomes of interest included postoperative hypothyroidism, euthyroidism, and persistent or recurrent hyperthyroidism without supplementation. Success was defined as postoperative euthyroidism or hypothyroidism. Failure was defined as persistent or recurrent hyperthyroidism.

RESULTS

Of the 14,245 patients, 4,546 underwent surgery [3,158 patients had subtotal thyroidectomy (STT) and 1,388 had total thyroidectomy (TT)] and 9,699 had radioactive iodine. The radioactive iodine group consisted of 2,383 patients receiving 1-10 mCi, 1,558 patients receiving 11-15 mCi, 516 patients receiving >15 mCi, and 5,242 patients receiving an unspecified amount. Surgery was found to be 3.44 times more likely to be successful than radioactive iodine (p < 0.001). STT and TT were found to be 2.33 and 94.45 times more likely to be successful than radioactive iodine (p < 0.001), respectively.

CONCLUSIONS

On the basis of the outcomes analyzed, surgery appears to be the most successful in the management of GD, with TT being the preferred surgical option.

Is subtotal thyroidectomy a cost-effective treatment for Graves disease? A cost-effectiveness analysis of the medical and surgical treatment options

BACKGROUND

The 3 treatment options for Graves disease (GD) are antithyroid drugs (ATDs), radioactive iodine (RAI), and thyroid surgery. We hypothesized that thyroid surgery is cost-effective for Graves disease when compared to RAI or ATD.

METHODS

Cost-effectiveness analysis was performed to compare operative strategies to medical treatment strategies for GD. The decision model, based on a reference case, included treatment outcomes, probabilities, and costs derived from literature review. Outcomes were weighted using quality of life utility factors, yielding quality-adjusted life years (QALYs). The uncertainty of costs, probabilities, and utility estimates in the model were examined by univariate and multivariate sensitivity analysis and Monte Carlo simulation.

RESULTS

The subtotal thyroidectomy strategy produced the greatest QALYs, 25.783, with an incremental cost-effectiveness ratio of $26,602 per QALY, reflecting a gain of 0.091 QALYs at an additional cost of $2416 compared to RAI. Surgery was cost-effective when the initial postoperative euthyroid rate was greater than 49.5% and the total cost was less than $7391. Monte Carlo simulation showed the subtotal thyroidectomy strategy to be optimal in 826 of 1000 cases.

CONCLUSION

This study demonstrates that subtotal thyroidectomy can be a cost-effective treatment for GD. However, a 49.5% initial postoperative euthyroid rate was a necessary condition for cost-effective surgical management of GD.

Analysis of ¹³¹I therapy and correlation factors of Graves' disease patients: a 4-year retrospective study

OBJECTIVE

To analyze the correlation therapeutic effects of first sufficiency ¹³¹I therapy in Graves' disease patients and improve its one-time curative ratio.

METHODS

Seven hundred and sixty-six patients (age range 12-77 years, mean 40.46 ± 13.12 years), including 237 men (range 12-77 years, 40.98 ± 12.64 years) and 529 women (range 14-75 years, 40.22 ± 13.34 years), who received the first I treatment were studied. The relevant examinations were performed before ¹³¹I therapy: the maximal radioactive iodine uptake of thyroid (RAIUmax), the effective half-life (EHL), the ultrasound of thyroid to calculate its weight, thyroid imaging with single-photon emission computed tomography and serum-free triiodothyronine (FT₃), free thyroxine (FT₄), sensitive thyroid-stimulating hormone (sTSH), anti-thyrotrophin receptor antibody (TRAb), thyroid-stimulating immunoglobulin, thyroglobulin antibody (TgAb), and anti-thyroid microsome antibody (TMAb). After the ¹³¹I dosage was determined, all the patients took ¹³¹I once orally. The ¹³¹I dosage range was 74-592 MBq (221.63 ± 100.64 MBq). A clinical and laboratory assessment was performed at 1, 3, 6, and 12 months after ¹³¹I therapy. Patients were divided into the clinically recovered group (symptoms and signs disappeared, free thyroid hormone levels were within or below the normal range, and sTSH was within or above the normal range) and the clinically unhealed group (symptoms and signs disappeared partially, free thyroid hormone levels were still above the normal range or within the normal range for a time and then increased again, and sTSH was constantly below the normal range). Data were analyzed by the unpaired t-test, the independent samples t-test, the χ² test, logistic regression, and Pearson bivariate correlation.

RESULTS

The one-time curative ratio of ¹³¹I therapy was 78.7% (including euthyroidism and hypothyroidism). Multiplicity in healing patients fit the logistic regression equation. The accuracy of discrimination of the equation was 79.5%. The influential factors of ¹³¹I therapy were age, RAIUmax, EHL, TRAb, and TgAb. RAIUmax and EHL were the protecting factors. Age, TRAb, and TgAb were the risk factors. TRAb influenced the one-time curative ratio between patients with negative and positive TRAb, which was higher in men (2.836 times) than in women (1.438 times).

CONCLUSION

¹³¹I therapy is an effective intervention for Graves' disease. The higher the RAIUmax and (or) the longer the EHL, the higher the possibility of a one-time cure. Elder patients or patients with a positive TRAb and (or) TgAb have a lower possibility of a one-time cure. Women with a positive TRAb should be administered an increased ¹³¹I dose to improve the curative effect.

The follow-up of radioiodine-treated hyperthyroid patients: should thyroid function be monitored more frequently?

BACKGROUND

There is a lack of data regarding the timing and particularly the severity of hypothyroidism post radioiodine (RI).

AIM

To investigate the timing and severity of hypothyroidism in RI-treated hyperthyroid patients.

METHODS

Retrospective examination of the records of 183 RI-treated hyperthyroid patients (79 autoimmune hyperthyroidism, 46 toxic multinodular goiter, and 58 hyperthyroidism of indeterminate etiology).

RESULTS

One hundred and fifty-nine patients requiring a single dose of RI (435 MBq), 107 (67%) developed hypothyroidism. Hypothyroidism detected in: 16% of patients at <8 weeks, 46% at 8 to <16 weeks, 24% at 16 to <24 weeks, 9% at 24 to <36 weeks, 3% at 36 to <52 weeks, and 2% at >52 weeks. One hundred and eighty-three patients had follow-up after one or more doses of RI and 124 (68%) patients developed hypothyroidism; of these, 44 (36%) had TSH>50 mU/l and 34 (27%) had free T4<5 pmol/l when hypothyroidism was first detected. Of those patients with a delayed outpatient visit (no.=77) and those with an outpatient visit within the recommended target interval (no.=47), median TSH was 23 (0.05-152) mU/l and 32 (0.05-150) mU/l, respectively (p=0.75) and median free T4 was 7.1 (1.3-16.7) pmol/l and 6.6 (1.3-15.4) pmol/l, respectively (p=0.21) at first detection of hypothyroidism.

CONCLUSIONS

The severity of hypothyroidism when first detected during follow-up is of concern and suggests that closer monitoring of thyroid function is required, particularly during the first 6 months post- RI therapy.

Gluten-free diet and autoimmune thyroiditis in patients with celiac disease. A prospective controlled study

OBJECTIVE

Early diagnosis and dietary treatment with a gluten-free diet might slow down the progression of associated autoimmune diseases in celiac disease, but the data are contradictory. We investigated the course of autoimmune thyroid diseases in newly diagnosed celiac disease patients before and after gluten-free dietary treatment.

MATERIAL AND METHODS

Twenty-seven consecutive adults with newly diagnosed celiac disease were investigated at the time of diagnosis and after 1 year on gluten-free diet. Earlier diagnosed and subclinical autoimmune thyroid diseases were recorded and examined. Thyroid gland volume and echogenicity were measured by ultrasound. Autoantibodies against celiac disease and thyroiditis, and thyroid function tests were determined. For comparison, 27 non-celiac controls on normal gluten-containing diet were examined.

RESULTS

At the time of diagnosis, the celiac disease patients had more manifest (n = 7) or subclinical (n = 3) thyroid diseases than the controls (10/27 vs. 3/27, p = 0.055). During the follow-up, the thyroid volume decreased significantly in the patients with celiac disease compared with the controls, indicating the progression of thyroid gland atrophy despite the gluten-free diet.

CONCLUSIONS

Celiac patients had an increased risk of thyroid autoimmune disorders. A gluten-free diet seemed not to prevent the progression of autoimmune process during a follow-up of 1 year.

A randomized trial evaluating a block-replacement regimen during radioiodine therapy

BACKGROUND

Lack of consensus regarding the antithyroid drug regimen in relation to radioiodine ((131) I) therapy of hyperthyroidism prompted this randomized trial comparing two strategies.

DESIGN

Patients with Graves' disease (GD, n = 51) or toxic nodular goitre (TNG, n = 49) were randomized to (131) I either 8 days following discontinuation of methimazole (-BRT, n = 52, median dose: 5 mg) or while on a continuous block-replacement regimen (+BRT, n = 48, median dose 15 mg methimazole and 100 μg levothyroxine). results: Patients in the +BRT group required more radioactivity. In this group, thyroid function did not change in the early post (131) I period, while serum-free T3 index was higher in the -BRT group (P < 0·05). One year posttherapy, the fraction of cured patients (euthyroid or hypothyroid) was 48% and 61% in the +BRT and -BRT group, respectively (P = 0·014 unadjusted; P = 0·004 adjusted), but the outcome depended on the type of disease. In GD, treatment failure in the +BRT group correlated positively with the 24-h thyroid (131) I uptake (P = 0·017), while no correlations existed in the -BRT group. In addition to +BRT allocation, patients with TNG were at higher risk of treatment failure with lower thyroid radiation doses (P = 0·048), higher doses of methimazole (P = 0·026) and lower levels of serum TSH (P = 0·009).

CONCLUSIONS

A continuous block-replacement regimen results in a stable thyroid function during (131) I therapy but is hampered by the higher amounts of radioactivity required. The study demonstrates that the outcome in GD is highly unpredictable, while treatment failure in patients with TNG is correlated with a number of factors.

Non-malignant thyroid diseases after a wide range of radiation exposures

The thyroid gland is one of the most radiosensitive human organs. While it is well known that radiation exposure increases the risk of thyroid cancer, less is known about its effects in relation to non-malignant thyroid diseases. The aim of this review is to evaluate the effects of high- and low-dose radiation on benign structural and functional diseases of the thyroid. We examined the results of major studies from cancer patients treated with high-dose radiotherapy or thyrotoxicosis patients treated with high doses of iodine-131, patients treated with moderate- to high-dose radiotherapy for benign diseases, persons exposed to low doses from environmental radiation, and survivors of the atomic bombings who were exposed to a range of doses. We evaluated radiation effects on structural (tumors, nodules), functional (hyper- and hypothyroidism), and autoimmune thyroid diseases. After a wide range of doses of ionizing radiation, an increased risk of thyroid adenomas and nodules was observed in a variety of populations and settings. The dose response appeared to be linear at low to moderate doses, but in one study there was some suggestion of a reduction in risk above 5 Gy. The elevated risk for benign tumors continues for decades after exposure. Considerably less consistent findings are available regarding functional thyroid diseases including autoimmune diseases. In general, associations for these outcomes were fairly weak, and significant radiation effects were most often observed after high doses, particularly for hypothyroidism. A significant radiation dose-response relationship was demonstrated for benign nodules and follicular adenomas. The effects of radiation on functional thyroid diseases are less clear, partly due to the greater difficulties encountered in studying these diseases.

Extremely high doses of radioiodine required for treatment of Graves' hyperthyroidism: a case report

Introduction

Radioactive iodine (131I) is widely prescribed for treatment of Graves' disease. A dose of 370 to 555 MBq (10 to 15 mCi) is usually enough, but reports of improved remission rates with single doses up to 20-30 mCi, and 38.5 mCi at most, exist.

Case presentation

A 53-year-old male patient was evaluated in September 2005, with symptoms of thyrotoxicosis for 2 years. He presented with tachycardia (130 bpm) and a large goiter. Thyrotropin was <0.01 uIU/ml (0,41-4,5), free thyroxin >7.77 ng/dl (0.9-1.8), anti-thyreoperoxidase antibody: 374 IU/ml (<35) and anti-thyroglobulin antibody: 749 IU/ml (<115). Ultrasound: diffuse goiter, no nodules; right lobe: 7.9 × 3.8 × 3.8 cm; left: 7.7 × 3.5 × 3.8 cm; isthmus: 1.6 cm. Propylthiouracil 300 mg t.i.d. and propranolol were prescribed. Thyroid 99mTc-pertechnetate uptake: 52% (0.35-1.7%) and estimated thyroid volume: 149 mL. After 30 days, he received 555 MBq (15 mCi) of 131I-iodide. Six months after radioiodine therapy, under methimazole 40 mg, thyroid stimulating hormone was 1.5 uIU/ml; free thyroxine 0.54 ng/dl. Methimazole was suspended. In 21 days, thyroid stimulating hormone was 0.03 uIU/ml; free thyroxine 0.96 ng/dl. Methimazole was reintroduced. One year later, thyroid stimulating hormone was <0.01 uIU/ml and free thyroxine >7.77 ng/dl. Thyroid 99mTc-pertechnetate uptake was 45% and estimated thyroid volume 144 mL. A 1110 MBq (30 mCi) radioiodine therpy was administered. He used Methimazole for 8 months, when overt hypothyroidism appeared (TSH: 25.30 uIU/ml; free thyroxine: 0.64 ng/dl). Methimazole was interrupted. Hyperthyroidism returned 6 weeks later (thyroid stimulating hormone <0.01 uIU/ml; free thyroxine >7.77 ng/dl). Thyroid 99mTc-pertechnetate uptake was 25% and estimated thyroid volume 111 mL. Methimazole was prescribed again. In March 2008 he received a 2590 MBq (70 mCi) radioiodine therapy. By may/2008, under methimazole 20 mg, his TSH was 0.07 uIU/ml; free thyroxine 1.31 ng/dl. In October 2008 he presented overt hypothyroidism (TSH 91.6 uIU/ml; free thyroxine 0.34) and was given levothyroxine 75 mcg/day. He remains euthyroid under hormone replacement.

Conclusion

Our presented case of Graves' disease received a cumulative dose of 4255 MBq (115 mCi). The high uptake could indicate accelerated iodine turnover with 131I short time of action. Impaired hormone synthesis could also be present. We believe the extremely high dose required was due to the initial very high iodine uptake and large thyroid volume.

Extremely high doses of radioiodine required for treatment of Graves' hyperthyroidism: a case report

INTRODUCTION

Radioactive iodine ((131)I) is widely prescribed for treatment of Graves' disease. A dose of 370 to 555 MBq (10 to 15 mCi) is usually enough, but reports of improved remission rates with single doses up to 20-30 mCi, and 38.5 mCi at most, exist.

CASE PRESENTATION

A 53-year-old male patient was evaluated in September 2005, with symptoms of thyrotoxicosis for 2 years. He presented with tachycardia (130 bpm) and a large goiter. Thyrotropin was <0.01 uIU/ml (0,41-4,5), free thyroxin >7.77 ng/dl (0.9-1.8), anti-thyreoperoxidase antibody: 374 IU/ml (<35) and anti-thyroglobulin antibody: 749 IU/ml (<115). Ultrasound: diffuse goiter, no nodules; right lobe: 7.9 x 3.8 x 3.8 cm; left: 7.7 x 3.5 x 3.8 cm; isthmus: 1.6 cm. Propylthiouracil 300 mg t.i.d. and propranolol were prescribed. Thyroid (99m)Tc-pertechnetate uptake: 52% (0.35-1.7%) and estimated thyroid volume: 149 mL. After 30 days, he received 555 MBq (15 mCi) of (131)I-iodide. Six months after radioiodine therapy, under methimazole 40 mg, thyroid stimulating hormone was 1.5 uIU/ml; free thyroxine 0.54 ng/dl. Methimazole was suspended. In 21 days, thyroid stimulating hormone was 0.03 uIU/ml; free thyroxine 0.96 ng/dl. Methimazole was reintroduced. One year later, thyroid stimulating hormone was <0.01 uIU/ml and free thyroxine >7.77 ng/dl. Thyroid (99m)Tc-pertechnetate uptake was 45% and estimated thyroid volume 144 mL. A 1110 MBq (30 mCi) radioiodine therpy was administered. He used Methimazole for 8 months, when overt hypothyroidism appeared (TSH: 25.30 uIU/ml; free thyroxine: 0.64 ng/dl). Methimazole was interrupted. Hyperthyroidism returned 6 weeks later (thyroid stimulating hormone <0.01 uIU/ml; free thyroxine >7.77 ng/dl). Thyroid (99m)Tc-pertechnetate uptake was 25% and estimated thyroid volume 111 mL. Methimazole was prescribed again. In March 2008 he received a 2590 MBq (70 mCi) radioiodine therapy. By may/2008, under methimazole 20 mg, his TSH was 0.07 uIU/ml; free thyroxine 1.31 ng/dl. In October 2008 he presented overt hypothyroidism (TSH 91.6 uIU/ml; free thyroxine 0.34) and was given levothyroxine 75 mcg/day. He remains euthyroid under hormone replacement.

CONCLUSION

Our presented case of Graves' disease received a cumulative dose of 4255 MBq (115 mCi). The high uptake could indicate accelerated iodine turnover with (131)I short time of action. Impaired hormone synthesis could also be present. We believe the extremely high dose required was due to the initial very high iodine uptake and large thyroid volume.

Radiometabolic treatment of hyperthyroidism with a calculated dose of 131-iodine: results of one-year follow-up

Oral administration of radioactive iodine (131I) is a well-known and effective procedure for the treatment of hyperthyroidism. However, the optimal dose is still a matter of debate, as is the frequency of recurrence and hypothyroidism. The aim of our study was to evaluate the 1-yr outcome of a calculated dose of 131I activity in the treatment of hyperthyroidism, following the guidelines published jointly by the Italian Society of Endocrinology and the Italian Society of Nuclear Medicine.We studied 84 patients affected with hyperthyroidism (55 with Graves' disease and 29 with toxic adenoma), who were treated with a dose of 131I activity obtained by using the formula from the guidelines. In all patients serum free T4, free T3, and TSH were measured before, and 2, 6, and 12 months after radiometabolic therapy. A thyroid scan and thyroid uptake with 131I were also performed before treatment, and a thyroid ultrasound scan was obtained before and 1 yr after treatment. One year after treatment, 22 out of 55 patients with Graves' diseases (40.0%) had persistence/ recurrence of hyperthyroidism, whereas only 1 patient of the 29 with toxic adenoma (3.4%) was still in a hyperthyroid state. The frequency of hypothyroidism in patients responsive to therapy was higher in subjects with Graves' disease (45.5%), than in those with toxic adenoma (17.3%, p=0.02). Overall size reduction of the target lesion was 56.2+/-23.1%. In conclusion, the dose calculation suggested by the guidelines represents an effective method for treating thyroid toxic adenoma. In subjects with Graves' disease, we propose using a pre-determined 131I activity, which is higher than that derived from the guidelines. Such an approach would reduce the incidence of recurrent/persistent hyperthyroidism. On the other hand, an increase in post-131I hypothyroidism should not be regarded as a negative effect in these patients, since hypothyroidism is easily corrected, and the risk of worsening ophthalmopathy is reduced.

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

CONTEXT

There is little consensus regarding the most appropriate dose of radioiodine ((131)I) to be administered to patients with hyperthyroidism.

OBJECTIVE

To compare the efficacy of fixed dose regimens of (131)I in curing hyperthyroidism and to define simple clinical and biochemical factors that predict outcome in individual patients.

DESIGN

Consecutive series of hyperthyroid subjects treated with (131)I.

SETTING

Single Secondary/Tertiary Care Hospital Clinic.

PARTICIPANTS

A total of 1278 patients (1013 females and 262 males, mean age 49.7 years) presenting with hyperthyroidism between 1984 and 2006.

INTERVENTION

Treatment with (131)I using a fixed dose regimen.

MAIN OUTCOME MEASURES

Probability of cure and risk of development of hypothyroidism following a single dose of (131)I.

RESULTS

Patients given a single dose of (131)I of 600 MBq (n = 485) had a higher cure rate (84.1%) compared with those receiving either 370 MBq (74.9%, P < 0.001) or those given 185 Bq (63%, P < 0.001). An increased incidence of hypothyroidism by 1 year was evident with higher doses (600 MBq: 60.4%; 370 MBq: 49.2%, P = 0.001; 185 Bq: 38.1%, P < 0.001). Binary logistic regression analysis identified a 600 Bq dose of (131)I [adjusted odds ratio, AOR 3.33 (2.28-4.85), P < 0.001], female gender [AOR 1.75 (1.23-2.47), P = 0.002], lower presenting serum free T4 concentration [AOR 1.01 (1.01-1.02), P < 0.001] and absence of a palpable goitre [AOR 3.33 (2.00-5.56), P < 0.001] to be independent predictors of cure. Similarly, a 600 MBq dose [AOR 3.79 (2.66-5.38), P < 0.001], female gender [AOR 1.46 (1.05-2.02), P = 0.02], younger age [AOR 1.03 (1.02-1.04), P < 0.001], absence of a palpable goitre [AOR 3.85 (2.38-5.88), P < 0.001] and presence of ophthalmopathy [AOR 1.57 (1.06-2.31), P = 0.02] were identified as independent factors predicting the probability of development of hypothyroidism at one year. Based on these findings, formulae to indicate probability of cure and risk of hypothyroidism for application to individual patients were derived.

CONCLUSIONS

Simple clinical/biochemical criteria can be used to predict outcome after (131)I treatment. These factors determine that males, those with severe biochemical hyperthyroidism, and those with a palpable goitre require larger doses (600 MBq) in order to achieve cure.

Long-term maintenance of low-dose antithyroid drugs versus drug withdrawal in patients with Graves' hyperthyroidism

OBJECTIVE

The relapse rate of Graves' hyperthyroidism after finishing an antithyroid cicle is high. The objective of this work was to prospectively investigate the relapse rate of Graves' hyperthyroidism (GH) in patients with maintenance of a low dose of antithyroid drug (ATD) therapy.

PATIENTS AND METHOD

From March 1997, all patients with GH consecutively attending the same center who remained euthyroid with low doses of synthetic ATD (carbimazole or methimazole: 2.5-5mg/day) on 2 consecutive follow-up visits (at 10-12 months) were included in this study. Instead of withdrawing ATD, the aim was to continue with this low dose for a 5-year period (group M: 53 patients). From March 1997, data were also collected from patients with GH who were consecutively followed-up and who, meeting the criteria for inclusion in group M, had stopped receiving ATD before the start of the study (March 1997) (group R: 31 patients).

MAIN OUTCOME

GH relapse was observed in 12/53 patients in group M (22.64%) and in 24/31 patients in group R (77.42%) (p<0.000).

CONCLUSIONS

The GH relapse rate was significantly lower with long-term maintenance of a low dose of ATD than with therapy withdrawal.

131 I-induced changes in rat thyroid gland function

Therapeutic doses of (131)I administered to thyrotoxic patients may cause thyroid failure. The present study used a rat model to determine thyroid function after the administration of different doses of (131)I (64-277 microCi). Thirty male Fisher rats in the experimental group and 30 in the control group (untreated) were followed for 6 months. The animals were 4 months old at the beginning of the experiment and were sacrificed at an age of 9 months. Hormone concentration was determined before (131)I administration (4-month-old animals) and three times following (131)I administration, when the animals were 7, 8, and 9 months old. The thyroid glands were removed and weighed, their volume was determined and histopathological examination was performed at the end of the experiment. Significant differences in serum triiodothyronine and thyroid-stimulating hormone concentration, measured at the age of 7, 8, and 9 months, were found in the experimental group. During aging of the animals, the concentration of thyroxin fell from 64.8 +/- 8.16 to 55.0 +/- 6.1 nM in the control group and from 69.4 +/- 6.9 to 25.4 +/- 3.2 nM in the experimental group. Thyroid gland volume and weight were significantly lower in the experimental than in the control group. Thyroid glands from the experimental group showed hyaline thickness of the blood vessel wall, necrotic follicles, a strong inflammatory reaction, and peeling of necrotic cells in the follicles. In conclusion, significant differences in hormone levels and histopathological findings indicated prolonged hypothyroidism after (131)I administration to rats, which was not (131)I dose dependent.

Increased long-term cardiovascular morbidity among patients treated with radioactive iodine for hyperthyroidism

OBJECTIVE

Previous studies suggest that hyperthyroid patients remain at increased risk of cardiovascular morbidity after restoring euthyroidism. The aim of this study was to compare the rate and causes of hospitalization of hyperthyroid patients treated with radioactive iodine (RAI) with those of an age- and gender-matched reference population in a long-term follow-up study.

PATIENTS AND MEASUREMENTS

A population-based cohort study with a median follow-up time of 9 years was conducted among 2611 hyperthyroid patients treated with RAI between 1969 and 2002 in Tampere University Hospital, and among 2611 reference subjects. Information on hospitalizations was obtained from the nationwide Hospital Discharge Registry. New events were analysed as the main outcome, including only the first hospitalization due to a given indication.

RESULTS

The rate of hospitalization due to cardiovascular disease (CVD) was higher among patients with hyperthyroidism than among the control population [637.1 vs. 476.4 per 10 000 person-years, rate ratio (RR) 1.12, 95% confidence interval (CI) 1.03-1.21]. The risk remained elevated up to 35 years after the RAI treatment. Hospitalizations due to atrial fibrillation (RR 1.35), cerebrovascular disease (RR 1.31), diseases of other arteries and veins (RR 1.22), hypertension (RR 1.20) and heart failure (RR 1.48) were more frequent in the patients than controls, while no such difference was found for coronary artery disease. Hospitalizations due to cancer, infectious and gastrointestinal diseases, and fractures were also more common in patients than in controls.

CONCLUSIONS

Hyperthyroidism increases hospitalizations due to CVDs. The excess risk is sustained decades after treatment. Patients treated for hyperthyroidism constitute a high-risk group for CVD and may benefit from preventive interventions.

Avaliação da radioiodoterapia com doses fixas de 10 e 15 mCi em pacientes com doença de graves

As opções terapêuticas para a hipertireoidismo da doença de Graves são as drogas antitireoidianas, a cirurgia e o radioiodo, porém nenhuma delas é considerada ideal pois não atuam diretamente na etiopatogênese da doença. O radioiodo vem sendo cada vez mais utilizado como primeira escolha, sendo um tratamento definitivo, seguro e de fácil administração. Há autores que preferem doses mais altas para induzir deliberadamente o hipotireoidismo, enquanto outros recomendam doses mais baixas que, a curto prazo, implicam menor incidência de hipotireoidismo e maior de eutireoidismo. Não há consenso sobre o melhor esquema de doses fixas a ser utilizado, sendo esse o principal enfoque deste estudo, no qual comparamos doses de 10 e 15 mCi. Dos 164 pacientes analisados, 61 (37,2%) foram submetidos a 10 mCi e 103 (62,8%), a 15 mCi de 131I. Na análise longitudinal, observou-se que a remissão do hipertireoidismo foi estatisticamente diferente no sexto mês (p < 0,001), sendo maior no grupo em que foi empregada a dose de 15 mCi. Contudo, foi semelhante nos dois grupos após 12 e 24 meses. É possível concluir que doses fixas de 10 e 15 mCi promovem semelhante remissão do hipertireoidismo após 12 meses de tratamento. A remissão do hipertireoidismo não teve associação com idade, sexo ou uso prévio de drogas antitireoidianas.

Hyperparathyroidism after radioactive iodine therapy

BACKGROUND

Radioactive iodine (RAI) treatment has been suggested to cause primary hyperparathyroidism (HPT). We describe a series of patients with HPT and a history of RAI exposure.

METHODS

Patient demographic and clinical information was evaluated, including the latency time to the development of HPT after RAI exposure.

RESULTS

We treated 11 patients with HPT and a history of RAI exposure. RAI treatment was administered for benign thyroid disease in 9 (82%) cases. Thirty-six cases of HPT after RAI exposure in the English literature were compiled for further analysis. In this collective experience, the average latency time to the development of HPT after RAI treatment was 13.5 +/- 9.1 years and was found to be inversely correlated with age at RAI exposure.

CONCLUSIONS

Patients who undergo RAI treatment are at risk of developing HPT, and this risk appears to increase in elderly patients. Serum calcium surveillance is recommended for patients who have undergone RAI treatment.

Increased cancer incidence after radioiodine treatment for hyperthyroidism

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

Cancer incidence, especially cancer of the stomach, kidney, and breast, was higher in patients treated with RAI for hyperthyroidism.

Ultrasonography thyroid volume estimation in hyperthyroid patients treated with individual radioiodine dose

Radioiodine (RAI) therapy is a safe and effective treatment for hyperthyroidism and individual doses are frequently administered. Initial thyroid volume (TV) is an important parameter for RAI therapy. Ultrasonography (US) is considered the most reliable method of determining TV. The aim of this study was to evaluate TV by means of US in a cohort of 75 hyperthyroid patients before and after RAI therapy. According to clinical examination, thyroid US and technetium-99m (99mTc)-pernechnetate scintiscan, the diagnosis of hyperthyroidism was multinodular goiter (MNG) in 27, diffuse goiter (DG) in 32 and uninodular goiter (UNG) in 16 patients. The RAI dose to be administered was calculated according to TV and RAI uptake, up to a maximum of 600 MBq. TV was further evaluated 1, 3 and 6-12 months after RAI therapy. The initial TV was 42.3+/-4.0 ml for MNG, 29.7+/-2.8 ml for DG and 34.5+/-3.7 ml for UNG. After 6-12 months a non-significant TV reduction was observed in the MNG group even though the fraction of initial TV was 53.3+/-6.5%. Moreover, a significant TV reduction was noticed in the DG group (8.8+/-2.3 ml; p<0.001). In this group the fraction of initial TV was 28.6+/-3.2% at 6-12 month evaluation. A less marked, though still significant (p=0.04) TV reduction (19.6+/-3.2 ml) was also observed in the UNG group, the fraction of initial TV being 57.8+/-5.3% 6-12 months after RAI. In the whole patient population there was no significant correlation between TV reduction or TV at the last examination and initial TV, RAI dosage, baseline free T4 and TSH levels. No correlation was found between clinical condition at the last examination and TV reduction. In conclusion, these data justify TV estimation by means of US in the protocol of individual RAI dose for the therapy of hyperthyroidism. Our follow-up documents a poorly predictable TV reduction in all clinical conditions, but this is more pronounced and predictable in patients with diffuse toxic goiter.

Effects of bone marrow cell transplant on thyroid function in an I131-induced low T4 and elevated TSH rat model

Background

We developed a study using low dose radioactive iodine creating an animal model of transient elevation of thyroid stimulating hormone (TSH). Male derived bone marrow cells were transplanted to asses their effect on thyroid function and their capability to repair the thyroid parenchyma.

Results

At 40 an 80 days after I¹³¹ treatment, the study groups TSH and T4 serum values both increased and decreased significantly respectively compared to the negative control group. Eight weeks after cell transplantation, neither TSH nor T4 showed a significant difference in any group. The mean number of SRY gene copies found in group I (Left Intracardiac Transplant) was 523.3 and those in group II (Intrathyroid Transplant) were only 73. Group III (No Transplant) and IV had no copies. Group I presented a partial restore of the histological pattern of rat thyroid with approximately 20% – 30% of normal-sized follicles. Group II did not show any histological differences compared to group III (Positive control).

Conclusion

Both a significant increase of TSH and decrease of T4 can be induced as early as day 40 after a low dose of I¹³¹ in rats. Restore of normal thyroid function can be spontaneously achieved after using a low dose RAI in a rat model. The use of BM derived cells did not affect the re-establishment of thyroid function and might help restore the normal architecture after treatment with RAI.

What Influences Early Hypothyroidism After Radioiodine Treatment for Graves' Hyperthyroidism?

OBJECTIVE

The objective of this study was to evaluate the factors influencing the occurrence of early hypothyroidism after radioiodine treatment of Graves' hyperthyroidism.

MATERIAL AND METHODS

Of 147 patients with Graves' disease (GD) treated with radioactive I-131 (RAI) in our thyroid clinic between July 2003 and December 2004, 84 were followed at 2 and 4 to 5 months after treatment. The age range was 12 to 75 years and the dosage range in these patients was 7.4 to 29.9 mCi. Twenty-four were males and 60 were females. Factors possibly contributing to post-RAI hypothyroidism are: dosage of I-131, age, gender, size of the gland, initial serum free T4, free T3, thyroid-stimulating hormone (TSH) levels, pretreatment with antithyroid drugs, radioactive iodine uptake, and duration of disease.

RESULTS

All patients had low TSH, elevated FT4, and elevated radioactive iodine uptake (RAIU) at 4 and/or 24 hours. Of the 84 patients followed, 46% of the males and 62% of the females became hypothyroid at 4 to 5 months (57% of the total). Twenty-one patients remained hyperthyroid and 14 patients became euthyroid. Multivariate analysis of these 84 patients showed no statistically significant single contributing factor for the development of early hypothyroidism.

CONCLUSION

The early onset of hypothyroidism after RAI in GD is very common (57%) and unpredictable. Thus, after RAI treatment, all patients must be closely monitored for the development of this disorder.

Phase I Single-Dose Study of Intracavitary-Administered Iodine-131-TM-601 in Adults With Recurrent High-Grade Glioma

Purpose

TM-601 binds to malignant brain tumor cells with high affinity and does not seem to bind to normal brain tissue. Preclinical studies suggest that iodine-131 (131I) –TM-601 may be an effective targeted therapy for the treatment of glioma. We evaluated the safety, biodistribution, and dosimetry of intracavitary-administered 131I-TM-601 in patients with recurrent glioma.

Patients and Methods

Eighteen adult patients (17 with glioblastoma multiforme and one with anaplastic astrocytoma) with histologically documented recurrent glioma and a Karnofsky performance status of ≥ 60% who were eligible for cytoreductive craniotomy were enrolled. An intracavitary catheter with subcutaneous reservoir was placed in the tumor cavity during surgery. Two weeks after surgery, patients received a single dose of 131I-TM-601 from one of three dosing panels (0.25, 0.50, or 1.0 mg of TM-601), each labeled with 10 mCi of 131I.

Results

Intracavitary administration was well tolerated, with no dose-limiting toxicities observed. 131I-TM-601 bound to the tumor periphery and demonstrated long-term retention at the tumor with minimal uptake in any other organ system. Nonbound peptide was eliminated from the body within 24 to 48 hours. Only minor adverse events were reported during the 22 days after administration. At day 180, four patients had radiographic stable disease, and one had a partial response. Two of these patients further improved and were without evidence of disease for more than 30 months.

Conclusion

A single dose of 10 mCi 131I-TM-601 was well tolerated for 0.25 to 1.0 mg TM-601 and may have an antitumoral effect. Dosimetry and biodistribution from this first trial suggest that phase II studies of 131I-TM-601 are indicated.

Variability of the administered radioiodine doses for the treatment of hyperthyroidism in Belgium

OBJECTIVE

When using radioiodine for hyperthyroidism there is no consensus regarding the administration of fixed or calculated doses. Guidelines do not specify the preferable approach or the parameters to use to calculate the dose. Therefore, the dose might be quite different with regard to the chosen procedure. This study was undertaken to evaluate the variability of the amount of radioiodine administered in Belgium in various cases of hyperthyroidism.

DESIGN AND PATIENTS

Twenty-one Belgian nuclear medicine physicians received summarized clinical files from 10 patients suffering from overt hyperthyroidism (n = 7) or subclinical hyperthyroidism (n = 3). Five patients had homogeneous goiters, one had multinodular goiter, and four had hot nodule. Participants had to determine the radioiodine dose (millicuries, mCi) they would give in each case.

RESULTS

Proposed doses varied between 2 mCi and 25 mCi. Mean proposed dose for nodular disease was 10.71 mCi; it was 6.79 mCi for homogeneous goiter. For individual cases, a difference between the lowest and the highest dose of more than 17 mCi was observed in more than 50% of the cases.

CONCLUSIONS

We believe that more precise guidelines are mandatory, underlying uncertainties, controversies but recommending however, as minimal and maximal doses to administer, as well as clinical and biological parameters, if any, to be taken into account in order to modulate these doses.

Nonsurgical approaches to the management of thyroid nodules

Epidemiologic studies have documented substantial increases in the frequency of nodular thyroid disease. This trend is largely due to the increasing detection of nodules by the routine use of sonography in clinical practice. Only a small percentage of the nodules currently being detected will prove to be malignant. The probability of malignancy is similar in nonpalpable and palpable nodules. Fine-needle aspiration cytology has a central role in identifying malignant nodules, which are generally treated with surgery. Most thyroid nodules are cytologically benign and can be managed nonsurgically. Nodules that are completely asymptomatic require follow-up without treatment. Cosmetic problems and/or compression-related symptoms may be indications for surgery. When surgery is contraindicated or refused, several nonsurgical approaches are available. These include levothyroxine therapy, radioiodine treatment, percutaneous ethanol injections, and the new technique of laser photocoagulation. Levothyroxine therapy is the most widely used approach, but its clinical efficacy and safety are controversial. Levothyroxine might, nonetheless, be appropriate in selected cases characterized by low risk for adverse effects and nodule characteristics associated with response to this type of therapy. Radioiodine is the therapy of choice for toxic nodules or for symptomatic nodular goiters when surgery is not possible. Percutaneous ethanol injection should be used, in our opinion, as the first-line therapy only for recurrent symptomatic cystic nodules. Laser therapy should be reserved for selected patients treated in experienced centers only. With these options, clinicians can personalize the management of nodular thyroid disease according to a careful cost-benefit analysis.

Antithyroid drug therapy of Graves' hyperthyroidism: realistic goals and focus on evidence

Only a minority of patients with hyperthyroidism caused by Graves' disease will experience cure of disease with a permanent euthyroid state without medication. Antithyroid drugs are useful in attaining euthyroidism, and most patients will gradually enter remission of the autoimmune abnormality after becoming euthyroid. A stable euthyroid state may be sustained by prolonged low-dose medication. The risk of relapse of hyperthyroidism after withdrawal of medication seems to be independent of duration of therapy, once remission has been induced. A number of risk factors influence the outcome of therapy and they should be evaluated when planning duration of therapy with antithyroid drugs.