Outcome following standardized 185 MBq dose 131I therapy for Graves' disease

The value of total thyroidectomy as the definitive treatment for Graves' disease: A single centre experience of 594 cases

PURPOSE

Thyroidectomy is the preferred approach as the definitive treatment for Graves' disease. The outcomes for total thyroidectomy in a large series of 594 patients, who were observed in the last decade, will be presented in this study.

METHODS

The study concerned a retrospective review of 594 patients, undergoing a total thyroidectomy for Graves' disease. The incidence of complications and outcomes on hyperthyroidism and correlated symptoms resolution were also evaluated.

RESULTS

The mean age of the patients was of 44.7 ± 12.7 years and 456 patients (76.7%) were females. The mean gland weight was 67.3 ± 10.8 g (range: 20-350 g) and, in 397 patients (66.8%), the gland weighed >40 g. The mean operative time was 125 ± 23.1 min (range: 65-212 min). Temporary and permanent hypocalcaemia developed in 241 (40.6%) and 3 patients (0.5%), respectively. Temporary and permanent recurrent laryngeal nerve palsy were recorded in 31 (5.2%) and 1 patients (0.16%) respectively. No patient developed a thyroid storm. On multivariate analysis, patient age ≤50 years (Odds ratio: 1; 95% Confidence Interval: 0.843-0.901) and thyroid weight >40 g (Odds ratio: 1; 95%, Confidence Interval: 0.852-0.974), were mainly associated with the occurrence of complications.

CONCLUSION

This high-volume surgeon experience demonstrates that total thyroidectomy is a safe and effective treatment for Graves' disease. It is associated with a very low incidence rate of post-operative complications, most of which are transitory; therefore, it offers a rapid and definitive control of hyperthyroidism and its related symptoms.

Radioiodine therapy versus antithyroid medications for Graves' disease

BACKGROUND

Graves' disease is the most common cause of hyperthyroidism. Both antithyroid medications and radioiodine are commonly used treatments but their frequency of use varies between regions and countries. Despite the commonness of the diagnosis, any possible differences between the two treatments with respect to long-term outcomes remain unknown.

OBJECTIVES

To assess the effects of radioiodine therapy versus antithyroid medications for Graves' disease.

SEARCH METHODS

We performed a systematic literature search in the Cochrane Library, MEDLINE and EMBASE and the trials registers ICTRP Search Portal and ClinicalTrials.gov. The date of the last search was September 2015 for all databases.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing the effects of radioiodine therapy versus antithyroid medications for Graves' disease with at least two years follow-up.

DATA COLLECTION AND ANALYSIS

Two authors independently screened titles and abstracts for relevance. One author carried out screening for inclusion, data extraction and 'Risk of bias' assessment and a second author checked this. We presented data not suitable for meta-analysis as descriptive data. We analysed the overall quality of evidence utilising the GRADE instrument.

MAIN RESULTS

We included two RCTs involving 425 adult participants with Graves' disease in this review. Altogether 204 participants were randomised to radioiodine therapy and 221 to methimazole therapy. A single dose of radioiodine was administered. The duration of methimazole medication was 18 months. The period of follow-up was at least two years, depending on the outcome measured. For most outcome measures risk of bias was low; for the outcomes health-related quality of life as well as development and worsening of Graves' ophthalmopathy risks of performance bias and detection bias were high in at least one of the two RCTs.Health-related quality of life appeared to be similar in the radioiodine and methimazole treatment groups, however no quantitative data were reported (425 participants; 2 trials; low quality evidence). The development and worsening of Graves' ophthalmopathy was observed in 76 of 202 radioiodine-treated participants (38%) and in 40 of 215 methimazole-treated participants (19%): risk ratio (RR) 1.94 (95% confidence interval (CI) 1.40 to 2.70); 417 participants; 2 trials; low quality evidence. A total of 35% to 56% of radioiodine-treated participants and 42% of participants treated with methimazole were smokers, which is associated with the risk of worsening or development of Graves' ophthalmopathy. Euthyroidism was not achieved by any participant being treated with radioiodine compared with 64/68 (94%) of participants after methimazole treatment (112 participants; 1 trial). In this trial thyroxine therapy was not introduced early in both treatment arms to avoid hypothyroidism. Recurrence of hyperthyroidism (relapse) in favour of radioiodine treatment showed a RR of 0.20 (95% CI 0.01 to 2.66); P value = 0.22; 417 participants; 2 trials; very low quality evidence. Heterogeneity was high (I² = 91%) and the RRs were 0.61 or 0.06 with non-overlapping CIs. Adverse events other than development of worsening of Graves' ophthalmopathy for radioiodine therapy were hypothyroidism (39 of 41 participants (95%) compared with 0% of participants receiving methimazole, however thyroxine treatment to avoid hypothyroidism was not introduced early in the radioiodine group - 104 participants; 1 trial; very low quality evidence) and drug-related adverse events for methimazole treatment (23 of 215 participants (11%) reported adverse effects likely related to methimazole therapy - 215 participants; 2 trials; very low quality evidence). The outcome measures all-cause mortality and bone mineral density were not reported in the included trials. One trial (174 participants) reported socioeconomic effects: costs based on the official hospital reimbursement system in Sweden for patients without relapse and methimazole treatment were USD 1126/1164 (young/older methimazole group) and for radioiodine treatment USD 1862. Costs for patients with relapse and methimazole treatment were USD 2284/1972 (young/older methimazole group) and for radioiodine treatment USD 2760.

AUTHORS' CONCLUSIONS

The only antithyroid drug investigated in the two included trials was methimazole, which might limit the applicability of our findings with regard to other compounds such as propylthiouracil. Results from two RCTs suggest that radioiodine treatment is associated with an increased risk of Graves' ophthalmopathy. Our findings suggest some benefit from radioiodine treatment for recurrence of hyperthyroidism (relapse) but there is uncertainty about the magnitude of the effect size.

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.

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.

Radioiodine therapy in patients with Graves' disease and the effects of prior carbimazole therapy

The use of radioiodine as the first line of treatment in Graves' disease is restricted in India because of its limited availability and an unrealistic risk perception associated with it. Additionally, the effectiveness of radioiodine ablation in Graves' disease is influenced by many factors. Prior medical antithyroid therapy is one such important factor.

AIMS

To analyze the efficacy of low dose radioiodine therapy (5 mCi) in treatment of naive patients of Graves' disease in comparison to that in which it was already primed with an antithyroid drug, carbimazole.

SETTINGS AND DESIGN

A non-randomized, interventional study conducted in the Department of Medicine and Endocrinology of a tertiary care institute in South India.

MATERIALS AND METHODS

The study had two groups; Group A (36 treatment naive, uncomplicated Graves' disease patients) and B (34 Graves' disease patients on carbimazole prior to radioiodine therapy). Both groups had baseline clinical, biochemical evaluation and were reassessed at 3 and 6 months for evaluating the clinical status for possible documentation of cure.

RESULTS

The cure rate was 61.1% in drug naive group and 58.8% in pretreated group at 6 months following radioiodine (P = 0.845). Higher baseline 999m technicium (99m Tc) uptake, male gender, BMI and higher baseline free thyroxine (fT4) level predicted treatment failure following radioiodine therapy.

CONCLUSIONS

Administration of carbimazole prior to low dose radioiodine therapy does not alter the efficacy of radioiodine. Low fixed dose (5 mCi) of radioactive iodine may be a safe and effective primary therapeutic option in Graves' disease patients pretreated with antithyroid drugs.

A study of the efficacy of radioiodine therapy with individualized dosimetry in Graves' disease: need to retarget the radiation committed dose to the thyroid

Although Iodine-131 (131I) therapy is fully validated for Graves' disease (GD), there is debate about radioiodine amount to be administered (prescribed activity), as well as the use of individualized dosimetry vs fixed 131I activity. The clinical outcome of 119 GD patients treated with 131I from 2003 to 2008 has been evaluated. The prescribed activity was calculated according to a dosimetric protocol taking into account several variables, including thyroid volume reduction during treatment. In addition, we performed a simulation according to other dosimetric protocols, by calculating the corresponding prescribed activities. The patients were followed up for at least 12 months after treatment. In the first period of observation (2003), a 120-200 Gray (Gy) radiation dose to the thyroid was prescribed, according to the guidelines published by the Italian Societies of Endocrinology, Nuclear Medicine and Medical Physics: hyperthyroidism cure with a single radioiodine administration was obtained in 53% of patients. This outcome raised up to 89% when a higher radiation dose to the target (200- 250 Gy) was prescribed, although the administered activities were still lower, as a rule, than the most commonly employed fixed activities (400-600 Mega-Becquerel--MBq). Our method showed a high level of individual dose optimisation, particularly when compared to simplified methods. In conclusion, the protocol adopted in this study ensures a satisfactory rate of hyperthyroidism cure, while administering quite low 131I activities, provided that an adequate committed radiation dose to the thyroid is prescribed. In this context, the dose indication given by the aforementioned guidelines should probably be revised.

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.

Thyroid echogenicity predicts outcome of radioiodine therapy in patients with Graves' disease

CONTEXT

Despite accounting for variations in gland size and iodine kinetics, the success of radioiodine therapy in patients with Graves' disease remains moderately common and unpredictable.

OBJECTIVES

We hypothesized that hypoechogenic glands, with large, densely packed cells, are more radiosensitive than normoechogenic glands, in which much radiation is wasted on more abundant colloid. We evaluated this hypothesis in a cohort of patients with Graves' disease.

DESIGN

This was a prospective trial of patients recruited during 4 yr and followed up 1 yr after radioiodine therapy.

SETTING

This trial was held in a university hospital-outpatient clinic.

PATIENTS

A total of 177 consecutive patients with first presentation of Graves' disease (28 males), 23-76 yr old, who relapsed after antithyroid therapy were included in the study.

INTERVENTION

The patients were assigned to an ablative target-absorbed dose of 200 Gy (n = 78) or randomly to 100 or 120 Gy of nonablative dose (n = 99).

MAIN OUTCOME MEASURES

The measures were incidences of hyperthyroidism, euthyroidism, and hypothyroidism at 12-month follow-up.

RESULTS

At follow-up there were 25 hyperthyroid, 44 euthyroid, and 108 hypothyroid patients. Compared with 96 patients with a hypoechogenic gland, in 81 patients with a normoechogenic gland, there were more hyperthyroid (22 vs. 7%) and euthyroid (41 vs. 11%), but less hypothyroid outcomes (37 vs. 81%; P < 0.0001). The other independent predictor of increased radioresistance was the large gland volume.

CONCLUSION

In patients with Graves' disease, normoechogenic and large glands are associated with increased radioresistance.

Subtotal Thyroidectomy: A Reliable Method to Achieve Euthyroidism in Graves’ Disease. Prognostic Factors

BACKGROUND

Subtotal thyroidectomy is a widely accepted surgical procedure for Graves' disease. The purpose of this work is to evaluate functional long-term results and determine predictive prognostic factors of postoperative thyroid function.

STUDY DESIGN

This is a retrospective study conducted on 202 patients with Graves' disease undergoing subtotal thyroidectomy during the period 1979-2002. Predictive prognostic factors of final thyroid status were investigated by logistic ordinal regression, and probability of hypothyroidism during the years of follow-up was obtained by the Kaplan-Meier method.

RESULTS

Surgery controlled hyperthyroidism in 196 out of 202 patients (97%). The probability of hypo-, eu-, and hyperthyroidism at 5 years was 62.1%, 35.5%, and 2.4%, respectively. No statistical change in thyroid function occurred in the follow-up after 60 months. Multivariate analysis by a logistic ordinal regression analysis showed that weight of the remnant, age, and gender seemed to influence long-term thyroid function. The higher rates of euthyroidism were obtained when the remnant weight was between 6 and 8 g. No recurrence or persistence of hyperthyroidism occurred with remnant weights under 5 g.

CONCLUSIONS

Subtotal thyroidectomy controlled hyperfunction symptoms in 97% of our patients. Cure (euthyroidism) of Graves' disease patients should be attempted by leaving a thyroid tissue remnant between 6 and 8 g. Even more significant, our results suggest that euthyroidism rates could be improved by leaving a smaller remnant in elderly women and greater remnants in young men.

The surgical management of Graves' disease

BACKGROUND

The historical aspects of the pathophysiology and treatment of Graves' disease are briefly discussed in this paper.

MATERIALS AND METHODS

The three treatment modalities of Graves' disease are anti-thyroid drug therapy, radioactive iodine therapy, and surgery. Although the majority of patients with Graves' disease in the U.S. are treated with radioactive iodine, surgery still plays an important role when patients cannot tolerate anti-thyroid drug therapy, when medical treatment is rejected by patients, or when surgery is deemed the fastest and safest route in managing the patient.

CONCLUSIONS

The indications for surgical management of Graves' disease are discussed with emphasis on available data supporting the extent of thyroid resection based on the incidences of hypothyroidism, recurrence of hyperthyroidism, recurrent laryngeal nerve injury and hypoparathyroidism.

Comparison of Different Thyroid Committed Doses in Radioiodine Therapy for Graves' Hyperthyroidism

Despite vast worldwide experience in the use of 131I for treating Graves' disease (GD), no consensus of opinion exists concerning the optimal method of dose calculation. In one of the most popular equations, the administered (131)I dose is directly proportional to the estimated thyroid gland volume and inversely proportional to the measured 24-hour radioiodine uptake. In this study, we compared the efficiency of different tissue-absorbed doses to induce euthyroidism or hypothyroidism within 1 year after radioiodine therapy in GD patients. The study was carried out in 134 GD patients (age, 53 +/- 14 year; range, 16-82 year; thyroid volume, 28 +/- 18 mL; range, 6-95 mL; average 24-hour thyroid uptake, 72%) treated with (131)I therapy. The average radioiodine activity administered to patients was 518 +/- 226 MBq (range, 111-1110). The corresponding average thyroid absorbed dose, calculated by a modified Medical Internal Radiation Dose (MIRD) equation was 376 +/- 258 Gy (range, 99-1683). One year after treatment, 58 patients (43%) were hypothyroid, 57 patients (43%) were euthyroid, and 19 patients (14%) remained hyperthyroid. The patients were divided into 3 groups: 150 Gy (n = 32), 300 Gy (n = 58) and >300 Gy (n = 44). No significant difference in the rate of recurrent hyperthyroidism was found among the 3 groups (150 Gy: 15%; 300 Gy: 14%; and > or =300 Gy: 14%; chi-square test, p = 0.72). Whereas, the rate of hypothyroidism in the 3 groups was significantly correlated with the dose (150 Gy: 30%; 300 Gy: 46%; >300 Gy: 71%; chi-square test, p = 0.0003). The results obtained in this study show no correlation between dose and outcome of radioiodine therapy (in terms of persistent hyperthyroidism) for thyroid absorbed doses > or =150 Gy, while confirming the relation between the thyroid absorbed dose and the incidence of hypothyroidism in GD patients.

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

OBJECTIVE

To determine the cumulative incidence of hypothyroidism during long-term follow-up in patients treated for hyperthyroidism by radioactive iodine (131)I (RAI) therapy, the significance of clinical factors in predicting the development of hypothyroidism, and the outcome after a fixed 7 mCi (259 MBq) dose of RAI.

DESIGN

Prospective cohort study of patients treated for hyperthyroidism by RAI.

PATIENTS AND MEASUREMENTS

Since 1965, details on 2043 patients treated by RAI therapy in Tampere University Hospital were entered into a computerized register. Following RAI treatment, thyroid status was monitored every 1-3 months during the first year, and subsequently at 1-3-year intervals until June 2002 or until the patient died or moved out of the Tampere University Hospital district. results The cumulative incidence of hypothyroidism in patients with Graves' disease and toxic multinodular goitre at 1, 10 and 25 years was 24%vs. 4%, 59%vs. 15% and 82%vs. 32%, respectively. In a Cox regression model, previous partial thyroidectomy [risk ratio (RR) = 1.63 in patients with Graves' disease and RR = 1.59 in those with toxic multinodular goitre] and age at the first RAI treatment (RR = 0.998 and RR = 0.996 per year) were statistically significantly associated with the development of hypothyroidism both in patients with Graves' disease and in those with toxic multinodular goitre. Antithyroid medication preceding RAI therapy (RR = 0.47) decreased and female gender (RR = 1.53) increased the risk of hypothyroidism only in patients with Graves' disease. Administration of a single dose of RAI resulted in the control of hyperthyroidism in 75% of patients, while two to six RAI treatments were needed in 25% of patients to achieve either a hypothyroid or a euthyroid state in both groups. None of the clinical factors studied was associated with the remission rate either in patients with Graves' disease or in those with toxic multinodular goitre. The remission rate did not differ between the patients who received a dose of RAI calculated according to the uptake of RAI and thyroid size and those who received an empirical dose of RAI. The fixed 7 mCi (259 MBq) dose of RAI cured 80% of patients.

CONCLUSION

RAI treatment is effective in treating hyperthyroidism in patients with Graves' disease, but hypothyroidism will develop in 82% of patients in 25 years. Because the development of hypothyroidism seems to be inevitable and unpredictable by any clinical factors, the objective of RAI treatment should be to minimize the persistence of hyperthyroidism with the simplest possible form of treatment. We recommend a fixed 7 mCi dose of RAI to be used as the first empirical dose in the treatment of hyperthyroidism, at least in Graves' disease.

Onset age is associated with outcome of radioiodine therapy in Graves' disease

Controversy remains regarding the optimal dose calculation with radioiodine therapy for patients with Graves' disease. Here, we focused our analysis on data concerning the patient's pretreatment background, an empirically set dose of radioiodine and the post-treatment thyroid function, and investigated those factors that affected the outcome. The subjects consisted of 38 patients diagnosed as having Graves' disease. All patients were hospitalized to undertake radioiodine therapy between 1989 and 1998 at our hospital. At the follow-up periods of 6-, 12-, and 36-months after therapy, we divided the patients into two groups: one group those who had hypothyroid function, and the other those who had normal or hyperthyroid function. At 6- and 12-months, 50% of the patients belonged to the hypothyroid function group, whereas at 36-months, 55% of them had hypothyroid function. Logistic regression analysis, with the objective variable being the post-treatment hypothyroidism after 12 months, revealed that the significant factor was the onset age. We suggested that the age at onset should be considered in patients with Graves' disease to determine the optional radioiodine dose for the therapy.

A mathematical model of optimized radioiodine-131 therapy of Graves' hyperthyroidism

BACKGROUND: The current status of radioiodine-131 (RaI) dosimetry for Graves' hyperthyroidism is not clear. Recurrent hyperthyroidism and iatrogenic hypothyroidism are two problems which interact such that trying to solve one leads to exacerbation of the other. Optimized RaI therapy has therefore begun to be defined just in terms of early hypothyroidism (ablative therapy) as physicians have given up on reducing hypothyroidism. METHODS: Optimized therapy is evaluated both in terms of the greatest separation of cure rate from hypothyroidism rate (non-ablative therapy) or in terms of early hypothyroidism (ablative therapy) by mathematical modeling of outcome after radioiodine and critically discussing the three common methods of RaI dosing for Graves' disease. RESULTS: Cure follows a logarithmic relationship to activity administered or absorbed dose, while hypothyroidism follows a linear relationship. The effect of including or omitting factors in the calculation of the administered I-131 activity such as the measured thyroid uptake and effective half-life of RaI or giving extra compensation for gland size is discussed. CONCLUSIONS: Very little benefit can be gained by employing complicated methods of RaI dose selection for non-ablative therapy since the standard activity model shows the best potential for cure and prolonged euthyroidism. For ablative therapy, a standard MBq/g dosing provides the best outcome in terms of cure and early hypothyroidism.

Radioiodine treatment of hyperthyroidism-prognostic factors for outcome

There is little consensus regarding the most appropriate dose regimen for radioiodine (131I) in the treatment of hyperthyroidism. We audited 813 consecutive hyperthyroid patients treated with radioiodine to compare the efficacy of 2 fixed-dose regimens used within our center (185 megabequerels, 370 megabequerels) and to explore factors that may predict outcome. Patients were categorized into 3 diagnostic groups: Graves' disease, toxic nodular goiter, and hyperthyroidism of indeterminate etiology. Cure after a single dose of 131I was investigated and defined as euthyroid off all treatment for 6 months or T4 replacement for biochemical hypothyroidism in all groups. As expected, patients given a single dose of 370 megabequerels had a higher cure rate than those given 185 megabequerels, (84.6% vs. 66.6%, P < 0.0001) but an increase in hypothyroidism incidence at 1 yr (60.8% vs. 41.3%, P < 0.0001). There was no difference in cure rate between the groups with Graves' disease and those with toxic nodular goiter (69.5% vs. 71.4%; P, not significant), but Graves' patients had a higher incidence of hypothyroidism (54.5% vs. 31.7%, P < 0.0001). Males had a lower cure rate than females (67.6% vs. 76.7%, P = 0.02), whereas younger patients (<40 yr) had a lower cure rate than patients over 40 yr old (68.9% vs. 79.3%, P < 0.001). Patients with more severe hyperthyroidism (P < 0.0001) and with goiters of medium or large size (P < 0.0001) were less likely to be cured after a single dose of 131I. The use of antithyroid drugs, during a period 2 wk before or after 131I, resulted in a significant reduction in cure rate in patients given 185 megabequerels 131I (P < 0.01) but not 370 megabequerels. Logistic regression analysis showed dose, gender, goiters of medium or large size, and severity of hyperthyroidism to be significant independent prognostic factors for cure after a single dose of 131I. We have demonstrated that a single fixed dose of 370 megabequerels 131I is highly effective in curing toxic nodular hyperthyroidism as well as Graves' hyperthyroidism. Because male patients and those with more severe hyperthyroidism and medium or large-sized goiters are less likely to respond to a single dose of radioiodine, we suggest that the value of higher fixed initial doses of radioiodine should be evaluated in these patient categories with lower cure rates.

Management guidelines for hyperthyroidism

Anti-thyroid drugs, surgery and radioiodine all represent effective forms of treatment for Graves' hyperthyroidism. There is, however, little consensus regarding the treatment of choice for specific cases. This lack of consensus prompted the development of guidelines for good practice in the management of hyperthyroidism for the United Kingdom. This chapter describes the process of development of this United Kingdom consensus statement, and associated audit measures, and highlights outstanding contentious issues in the management of Graves' hyperthyroidism.

Influence of compensated radioiodine therapy on thyroid volume and incidence of hypothyroidism in Graves' disease

OBJECTIVES

To investigate the long-term effect of radioactive iodine (131I) on thyroid function and size in patients with Graves' disease.

SETTING

Out-patient clinic in Herlev Hospital.

SUBJECTS

One hundred and seventeen consecutive patients (104 women) with Graves' disease selected for 131I treatment and followed for a minimum of 12 months (range 1-10 years, median 5 years).

INTERVENTIONS

131I dose was calculated based on thyroid volume and 24-h 131I uptake.

MAIN OUTCOME MEASURES

Standard thyroid function variables and ultrasonically determined thyroid volume before treatment as well as 0.75, 1.5, 3, 6 and 12 months after treatment, and then once a year were investigated.

RESULTS

Seventy-eight patients were cured by one 131I dose and 30 by two doses, while the remaining nine patients received additional doses (range one to five doses, median one dose). Within one year, 25% developed hypothyroidism, and hereafter, hypothyroidism developed at a constant rate of 3% per year independent of antithyroid pretreatment. The cumulative 10-year risk of hypothyroidism was 60%. Initial median thyroid volume was 33 mL (range 9-106 mL). At 12 months after the last 131I dose, median thyroid volume was reduced to 14 mL (range 6-36 mL) (P < 0.00001). The median reduction being 58% (range 0-80%), hereafter no further reduction occurred. A significant reduction in thyroid volume was also noted in patients needing subsequent 131I doses and in those developing hypothyroidism within the first year.

CONCLUSIONS

131I normalizes thyroid volume in patients with Graves' disease. Hypothyroidism seems an inevitable end result of this treatment. The present study suggests that it will be impossible to modify 131I therapy in a way to achieve both early control of hyperthyroidism and a low incidence of hypothyroidism.

Is calculation of the dose in radioiodine therapy of hyperthyroidism worth while?

OBJECTIVE

The persistent controversy as to the best approach to radioiodine dose selection in the treatment of hyperthyroidism led us to perform a study in order to compare a fixed dose regime comprising doses of 185 370 or 555 MBq based on gland size assessment by palpation only, with a calculated 131I dose based on type of thyroid gland (diffuse, multinodular, solitary adenoma), an accurate thyroid volume measurement, and a 24-hour 131I uptake determination.

DESIGN

Prospective randomized study.

PATIENTS

Two hundred and twenty-one consecutive hyperthyroid patients referred for 131I treatment. Four Patients who died for reasons unrelated to hyperthyroidism, 7 lost to follow-up and 47 who did not receive antithyroid drugs after treatment, were excluded. The remaining 163 patients (143 women) were studied, divided into subgroups according to the type of gland. They all received antithyroid drugs prior to 131I treatment and this was resumed 7 days after treatment for a period of 3 weeks.

MEASUREMENTS

Thyroid function variables were determined approximately 2 weeks before 131I treatment, and again 1, 2, 3, 6, 9 and 12 months after treatment. Prior to 131I therapy the size of the thyroid gland was determined by ultrasound and a 24-hour uptake of 131I was carried out. Thyroid volume was also estimated 12 months after 131I therapy in 78 of the 163 patients. Twelve months after the initial 131I dose patients could be classified as euthyroid, hyperthyroid or hypothyroid.

RESULTS

Neither in the group of 163 patients nor within the three subgroups of hyperthyroidism could any significant difference in outcome between the two treatment regimes be demonstrated. Thirty-two of 78 patients (41%) in the calculated dose group and 30 of 85 patients (35%, NS) in the fixed group were classified as hyperthyroid. Seven of 78 (9%) in the calculated dose group and 6 out of 85 (7%, NS) in the fixed dose group were classified as permanently hypothyroid. Finally, 39 of 78 (50%) in the calculated dose group and 49 of 85 (58%, NS) in the fixed group were euthyroid at 12 months after 131I treatment. One year after 131I therapy thyroid volume was reduced from 59.3 +/- 9.2 (mean +/- SEM) to 36.2 +/- 6.6 ml (average reduction 39%) in the calculated dose group (P < 0.001). This reduction did not differ significantly from the fixed dose group where thyroid volume declined from 61.6 +/- 6.1 to 41.17 +/- 4.7 ml (average reduction 32%) (P < 0.001).

CONCLUSIONS

A semiquantitative approach is probably as good as the more elaborately calculated radioiodine dose for treatment of hyperthyroidism. It is clearly more cost effective and allows the use of predetermined standard doses.

Radioiodine therapy of Graves' hyperthyroidism: standard vs. calculated 131iodine activity. Results from a prospective, randomized, multicentre study

The present prospective, randomized, multicentre study was performed to directly compare for the first time the effectiveness of a standard activity of 555 MBq 131iodine vs. an activity calculated to deliver 100 Gy for treatment of Graves' thyrotoxicosis. Therapeutic success was defined as the elimination of hyperthyroidism 6 months after radioiodine application (range 4.5-8 months). A success rate of more than 90% in eliminating hyperthyroidism was reported for both approaches, but only in retrospective investigations. Investigated prospectively, hyperthyroidism was eliminated in only 71% of the patients receiving standard activity (70/98) and 58% of those randomized for calculated activity (62/107). In the patients with standard activity, therapeutic success was inversely related to thyroid size. The rate was 100% for thyroid volumes < or = 15 mL, 95% for 16-30 mL, 68% for 31-45 mL, 44% for 46-50 mL, 20% for 61-75 mL and 25% for > or = 75 mL. In those patients with an activity calculated to deliver 100 Gy (except in those with a volume < or = 15 mL) this size/outcome dependency was almost compensated. The rates were 86%, 65%, 45%, 61%, 41% and 45%, respectively. Furthermore, detailed statistical analysis revealed a strong correlation between the success of therapy and the radiation dose actually absorbed by the thyroid. The rate was 11% for a target dose of 50 Gy, 50% for 100 Gy, 67% for 150 Gy, 80% for 200 Gy, 84% for 250 Gy, 88% for 300 Gy, 90% for 350 Gy and 93% for 400 Gy.(ABSTRACT TRUNCATED AT 250 WORDS)

The management of hyperthyroidism

Although effective treatments for hyperthyroidism are available, none is perfect. Particularly with respect to Graves' disease, what is needed is a therapy directed at modulating the disease process itself rather than merely reducing the synthesis and secretion of thyroid hormones in the hope that the underlying Graves' disease will remit. Greater understanding of the pathogenesis of Graves' disease, resulting from cloning of the thyrotropin receptor and better knowledge of the interactions between these receptors or other thyroid antigens and the immune system, may lead to such treatment. Broad-spectrum immunosuppression, with all its side effects, is not the answer; more focused therapies to inhibit the immune response to specific thyroid antigens may represent the treatment of the future. Meanwhile, radioiodine therapy is the most effective and convenient method of achieving long-term control of hyperthyroidism, although at the cost of hypothyroidism in many patients.

Results of long-term follow-up after compensated fixed-dose therapy for thyrotoxicosis

To evaluate the effects of simple compensated fixed-dose iodine-131 therapy for thyrotoxicosis, the long-term results for 74 patients treated with a fixed dose of iodine-131 ranging from 5 to 12 mCi (185 to 444 MBq) were evaluated in the first 2 years of a trial. The dose selected was loosely based on the gross size of the thyroid gland. Routine antithyroid drug therapy was given for a minimum of 3 months after iodine-131 therapy. The mean (+/- SD) duration of follow-up was 74.5 +/- 42 months. The results indicated that roughly 25% of patients treated in this way will become hypothyroid after 5 years and that 85% are cured (need no further therapy during the follow-up period) using a single dose of iodine-131. Of those cured using a single iodine-131 dose, 81% were no longer receiving drugs after 6 months and 85% after 1 year. Such a regimen seems currently to be among the best available where prolonged periods of medication-free euthyroidism after therapy are sought.

The incidence of recurrence and hypothyroidism following treatment with antithyroid drugs, surgery or radioiodine in all patients with thyrotoxicosis in Malmö during the period 1970-1974

The incidence of recurrence and of hypothyroidism was determined in all new patients treated for thyrotoxicosis during the period 1970-1974 in an unselected, well-defined urban population. A total of 309 patients were followed up for a median time period of 108 (1-192) months. There was a cumulative incidence of 51% recurrence in patients who were treated with antithyroid drugs for Graves' thyrotoxicosis, whereas after surgery or radioiodine treatment there were few recurrences, but 32% and 78% cumulative incidences of hypothyroidism. There were no recurrences after surgery or radioiodine treatment in patients with toxic multinodular goitre or solitary toxic adenoma, but 29% and 40% cumulative incidences of hypothyroidism following radioiodine treatment. Late hypothyroidism occurred after surgery for Graves' thyrotoxicosis, and in all groups treated with radioiodine. Thus it is advisable that all patients with Graves' thyrotoxicosis, regardless of treatment, and all patients with toxic multinodular goitre or solitary toxic adenoma treated with radioiodine, should be followed up for many years, and probably for life.

Long-term follow-up of treatment of thyrotoxicosis by three different methods

In view of continuing debate regarding the best definitive therapy for thyrotoxicosis, we examined the long-term outcome of radioiodine (131I) or surgical treatment of 1918 thyrotoxic patients divided into three groups: those given 131I at a dose calculated from thyroid size, 131I uptake and effective half-life to administer a fixed radioactivity dose to the thyroid; those treated with a dose of 131I (110, 185 or 370 MBq) chosen empirically; and those treated by partial thyroidectomy. A minimum 10-year follow-up was achieved for 1119 patients treated with a calculated 131I dose; a single dose resulted in control of disease in 90.5%. At 5 years, 18% were hypothyroid, the prevalence rising to 42% at 20 years. Of 504 patients treated with an empirical 131I dose and followed for at least 5 years, thyrotoxicosis was controlled by a single dose in 89.7%. The rate of hypothyroidism at 5 years (38.5%) was higher than that found in the calculated dose group. A minimum 10-year follow-up was achieved for 295 surgically treated patients; thyrotoxicosis was controlled in 89.2%. The prevalence of hypothyroidism (2% at 5 years, 27.5% at 20 years) was lower than that found after 131I, whether given by calculated or empirical dose. Each of the treatments employed resulted in an acceptable rate of cure of thyrotoxicosis. If maintenance of euthyroidism is the major objective, our findings suggest that surgery represents the treatment of choice. Furthermore, calculated dose 131I administration has advantages in terms of risk of hypothyroidism over empirical dose treatment.(ABSTRACT TRUNCATED AT 250 WORDS)