Radioiodine therapy in Graves' disease based on tissue-absorbed dose calculations: effect of pre-treatment thyroid volume on clinical outcome

This study was performed with three aims. The first was to analyse the effectiveness of radioiodine therapy in Graves' disease patients with and without goitres under conditions of mild iodine deficiency using several tissue-absorbed doses. The second aim was to detect further parameters which might be predictive for treatment outcome. Finally, we wished to determine the deviation of the therapeutically achieved dose from that intended. Activities of 185-2,220 MBq radioiodine were calculated by means of Marinelli's formula to deliver doses of 150, 200 or 300 Gy to the thyroids of 224 patients with Graves' disease and goitres up to 130 ml in volume. Control of hyperthyroidism, change in thyroid volume and thyrotropin-receptor antibodies were evaluated 15+/-9 months after treatment for each dose. The results were further evaluated with respect to pre-treatment parameters which might be predictive for therapy outcome. Thyroidal radioiodine uptake was measured every day during therapy to determine the therapeutically achieved target dose and its coefficient of variation. There was a significant dose dependency in therapeutic outcome: frequency of hypothyroidism increased from 27.4% after 150 Gy to 67.7% after 300 Gy, while the frequency of persistent hyperthyroidism decreased from 27.4% after 150 Gy to 8.1% after 300 Gy. Patients who became hypothyroid had a maximum thyroid volume of 42 ml and received a target dose of 256+/-80 Gy. The coefficient of variation for the achieved target dose ranged between 27.7% for 150 Gy and 17.8% for 300 Gy. When analysing further factors which might influence therapeutic outcome, only pre-treatment thyroid volume showed a significant relationship to the result of treatment. It is concluded that a target dose of 250 Gy is essential to achieve hypothyroidism within 1 year after radioiodine therapy in Graves' disease patients with goitres up to 40 ml in volume. Patients with larger goitres might need higher doses.     

Radioiodine treatment of hyperthyroidism using a simplified dosimetric approach. Clinical results

PURPOSE: To evaluate the clinical effectiveness of a simplified dosimetric approach to the iodine-131 treatment of hyperthyroidism due to Graves' disease or uninodular and multinodular toxic goiter. MATERIAL AND METHODS: We enrolled 189 patients with biochemically confirmed hyperthyroidism and performed thyroid ultrasonography and scintigraphy obtaining the diagnosis of Graves' disease in 43 patients, uninodular toxic goiter in 57 patients and multinodular toxic goiter in 89 patients. In 28 patients we found cold thyroid nodules and performed fine-needle aspiration with negative cytology for thyroid malignancy in all cases. Antithyroid drugs were stopped 5 days till radioiodine administration and, if necessary, restored 15 days after the treatment. Radioiodine uptake test was performed in all patients and therapeutic activity calculated to obtain a minimal activity of 185 MBq in the thyroid 24 hours after administration. The minimal activity was adjusted based on clinical, biochemical and imaging data to obtain a maximal activity of 370 MBq after 24 hours. RESULTS: Biochemical and clinical tests were scheduled at 3 and 12 months posttreatment and thyroxine treatment was started when hypothyroidism occurred. In Graves' disease patients a mean activity of 370 MBq (distribution 259-555 MBq) was administered. Three months after treatment and at least 15 days after methimazole discontinuation 32 of 43 (74%) patients were hypothyroid, 5 of 43 (11%) euthyroid and 6 of 43 (15%) hyperthyroid. Three of the latter were immediately submitted to a new radioiodine administration while 32 hypothyroid patients received thyroxine treatment. One year after the radioiodine treatment no patient had hyperthyroidism; 38 of 43 (89%) were on a replacement treatment while 5 (11%) remained euthyroid. In uni- and multinodular toxic goiter a mean activity of 444 MBq (distribution 259-555 MBq) was administered. Three months posttreatment 134 of 146 (92%) patients were euthyroid and 12 of 146 (8%) patients hyperthyroid. Two patients were immediately submitted to a new radioiodine administration. One year posttreatment 142 of 146 (97%) patients were euthyroid while only 4 of 146 (3%) patients showed TSH levels above the normal range. Only 2 of them required thyroxine treatment. CONCLUSIONS: The simplified dosimetric method illustrated in our paper is very effective in clinical practice because it permits to avoid resorting to sophisticated but also imprecise quantitative methods. Hypothyroidism should not be considered as a major collateral effect of radioiodine treatment, particularly in Graves' disease. In fact, the pathogenesis of the disease requires an ablative treatment with both surgery and radioidine treatment and the control of hyperthyroidism and the prevention of relapse are the major clinical targets. Vice versa, hypothyroidism was very uncommon in uni- and multinodular toxic goiter when our dosimetric approach was applied.     

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.     

Determination of the optimal minimum radioiodine dose in patients with Graves' disease: a clinical outcome study.

The study was performed under the auspices of the International Atomic Energy Commission, Vienna, Austria, with the aim of determining the optimal minimum therapeutic dose of iodine-131 for Graves' disease. The study was designed as a single-blinded randomised prospective outcome trial. Fifty-eight patients were enrolled, consisting of 50 females and 8 males aged from 17 to 75 years. Each patient was investigated by clinical assessment, biochemical and immunological assessment, thyroid ultrasound, technetium-99m thyroid scintigraphy and 24-h thyroid 131I uptake. Patients were then randomised into two treatment groups, one receiving 60 Gy and the other receiving 90 Gy thyroid tissue absorbed dose of radioiodine. The end-point markers were clinical and biochemical response to treatment. The median follow-up period was 37.5 months (range, 24-48 months). Among the 57 patients who completed final follow-up, a euthyroid state was achieved in 26 patients (46%), 27 patients (47%) were rendered hypothyroid and four patients (7%) remained hyperthyroid. Thirty-four patients (60%) remained hyperthyroid at 6 months after the initial radioiodine dose (median dose 126 MBq), and a total of 21 patients required additional radioiodine therapy (median total dose 640 MBq; range 370-1,485 MBq). At 6-month follow-up, of the 29 patients who received a thyroid tissue dose of 90 Gy, 17 (59%) remained hyperthyroid. By comparison, of the 28 patients who received a thyroid tissue dose of 60 Gy, 17 (61%) remained hyperthyroid. No significant difference in treatment response was found (P=0.881). At 6 months, five patients in the 90-Gy group were hypothyroid, compared to two patients in the 60-Gy group (P=0.246). Overall at 6 months, non-responders to low-dose therapy had a significantly larger thyroid gland mass (respective means: 35.9 ml vs 21.9 ml) and significantly higher levels of serum thyroglobulin (respective means: 597.6 microg/l vs 96.9 microg/l). Where low-dose radioiodine treatment of Graves' disease is considered, a dose of 60 Gy will yield a 39% response rate at 6 months while minimising early hypothyroidism. No significant advantage in response rate is gained by using a dose of 90 Gy. For more rapid therapeutic effect at the expense of an increased rate of hypothyroidism, doses in excess of 120 Gy may be required. Ultrasound determination of thyroid mass and measurement of serum thyroglobulin levels may be predictive of those patients who will be less responsive to low-dose therapy.     

Determination of the optimal minimum radioiodine dose in patients with Graves' disease: a clinical outcome study

The study was performed under the auspices of the International Atomic Energy Commission, Vienna, Austria, with the aim of determining the optimal minimum therapeutic dose of iodine-131 for Graves' disease. The study was designed as a single-blinded randomised prospective outcome trial. Fifty-eight patients were enrolled, consisting of 50 females and 8 males aged from 17 to 75 years. Each patient was investigated by clinical assessment, biochemical and immunological assessment, thyroid ultrasound, technetium-99m thyroid scintigraphy and 24-h thyroid ¹³¹I uptake. Patients were then randomised into two treatment groups, one receiving 60 Gy and the other receiving 90 Gy thyroid tissue absorbed dose of radioiodine. The end-point markers were clinical and biochemical response to treatment. The median follow-up period was 37.5 months (range, 24-48 months). Among the 57 patients who completed final follow-up, a euthyroid state was achieved in 26 patients (46%), 27 patients (47%) were rendered hypothyroid and four patients (7%) remained hyperthyroid. Thirty-four patients (60%) remained hyperthyroid at 6 months after the initial radioiodine dose (median dose 126 MBq), and a total of 21 patients required additional radioiodine therapy (median total dose 640 MBq; range 370-1,485 MBq). At 6-month follow-up, of the 29 patients who received a thyroid tissue dose of 90 Gy, 17 (59%) remained hyperthyroid. By comparison, of the 28 patients who received a thyroid tissue dose of 60 Gy, 17 (61%) remained hyperthyroid. No significant difference in treatment response was found (P=0.881). At 6 months, five patients in the 90-Gy group were hypothyroid, compared to two patients in the 60-Gy group (P=0.246). Overall at 6 months, non-responders to low-dose therapy had a significantly larger thyroid gland mass (respective means: 35.9 ml vs 21.9 ml) and significantly higher levels of serum thyroglobulin (respective means: 597.6 µg/l vs 96.9 µg/l). Where low-dose radioiodine treatment of Graves' disease is considered, a dose of 60 Gy will yield a 39% response rate at 6 months while minimising early hypothyroidism. No significant advantage in response rate is gained by using a dose of 90 Gy. For more rapid therapeutic effect at the expense of an increased rate of hypothyroidism, doses in excess of 120 Gy may be required. Ultrasound determination of thyroid mass and measurement of serum thyroglobulin levels may be predictive of those patients who will be less responsive to low-dose therapy.     

Dose selection for radioiodine therapy of borderline hyperthyroid patients with multifocal and disseminated autonomy on the basis of 99mTc-pertechnetate thyroid uptake

The aim of this study was to optimise radioiodine therapy of diffuse and nodular toxic goitre by calculation of the radiation dose delivered to the thyroid on the basis of the pretreatment technetium-99m pertechnetate thyroid uptake under thyrotropin suppression (TcTU(s)). The TcTU(s) value serves as a substitute for the non-suppressible iodine turnover and the functional autonomous mass. Marinelli's formula was used to calculate tissue absorbed doses of 150 Gy, 200 Gy, 250 Gy and 300 Gy to the thyroids of 438 patients with multifocal and disseminated autonomy. The mean age of patients was 70+/-9 years, and the mean thyroid volume was 54+/-26 ml. Two hundred and sixty-one of the patients had at least one documented previous episode of overt hyperthyroidism. Tissue absorbed doses were adapted to the pretreatment TcTU(s): 150 Gy for a TcTU(s) of 1.5%-2.49%, 200 Gy for a TcTU(s) of 2.5%-3.49%, 250 Gy for a TcTU(s) of 3.5%-4.49% and 300 Gy for a TcTU(s) of > or =4.5%. Normalisation of TcTU(s) and thyrotropin (TSH), thyroid volume reduction and frequency of hypothyroidism and recurrent hyperthyroidism were evaluated 1 year after a single radioiodine therapy. The presented dose strategy resulted in normalisation of TcTU(s) in 96% and an increase in TSH to the normal range in 92%. Recurrent hyperthyroidism was observed in only five patients. Thyroid volume decreased from 54+/-26 before treatment to 34+/-20 ml, a mean reduction of 37%. The frequency of hypothyroidism, at 0.9%, was encouragingly low. Dose selection in accordance with pretreatment TcTU(s) can be recommended for elimination of functional autonomous tissue with a single radioiodine therapy in patients of advanced age with enlarged thyroid glands and relevant autonomous masses who are at risk of developing iodine-induced hyperthyroidism.     

Single dose planning for radioiodine-131 therapy of Graves’ disease

Objective  Patients with Graves’ disease were studied one year after radioiodine-131 therapy to assess the relationship between the effectiveness of the therapy and the radioiodine doses used.Methods: Patients were classified into three groups according to thyroid function as hyperthyroidism, euthyroidism and hypothyroidism at one year after I-131 therapy. In these groups we compared the mean values of dose, dose per thyroid weight calculated with I-123 uptake before the therapy (pre D/W), dose per thyroid weight calculated with therapeutic I-131 uptake (post D/W), and absorbed dose. Results  No significant differences were found between the three groups in terms of dose or pre D/W. The mean values of post D/W and absorbed dose in the non-hyperthyroid (euthyroid and hypothyroid) group were significantly greater than those in the hyperthyroid group. Post D/W of 6.3 MBq/g was a threshold separating the non-hyperthyroid group from the hyperthyroid group. There was no correlation between pre D/W and post D/W; however, the mean post D/W was significantly greater than the mean pre D/W. All patients with pre D/W above 6.3 MBq/g showed non-hyperthyroidism at one year after the radioiodine treatment. Conclusions  No indicators before the radioiodine therapy had significant relationships with the effectiveness of the therapy at one year after the treatment. However, the single therapy planned for setting the pre D/W above 6.3 MBq/g will certainly make the patients non-hyperthyroid. As this proposal of dose planning is based on a small number of patients, further study is needed.     

Radioiodine-treatment (RIT) of functional thyroidal autonomy

Since 1942, therapy with radioiodine (RIT) has gained a major role in the treatment of benign thyroid disorders, notably hyperthyroidism caused by Graves' disease or toxic multinodular goitre (thyroid autonomy). In iodine deficient areas thyroid autonomy accounts for 40-50% of all cases with hyperthyroidism. RIT has become a cost-effective first-line procedure in autonomy-patients with latent or overt hyperthyroidism, especially in the absence of a large goitre, after thyroid surgery and in elderly patients with associated conditions who carry a high intra- or perioperative risk. Decisions concerning the definitive treatment of thyroid autonomy should take into account previous episodes of hyperthyroidism, objective parameters of risk stratification in euthyroid patients as well as concomitant diseases and the probability of iodine exposure in the future. In Central Europe the majority of investigators prefer to estimate the therapeutic activity individually by a radioiodine test. TCTUs (global 99m-Tc-pertechnetate thyroid uptake under suppression)-based dose concepts have been proven to be highly effective in the elimination of autonomy and carry a low (< 10%) risk of post-radioiodine-therapeutic hypothyroidism. Radioiodine therapy for autonomy has been found to be both effective and safe and without major early or late side effects. The most frequent complication is hypothyroidism requiring lifelong follow-up.     

Low failure rate of fixed administered activity of 400 MBq 131I with pre-treatment with carbimazole for thyrotoxicosis: the Gateshead Protocol

BACKGROUND: Thyrotoxicosis is associated with significant morbidity, therefore adequate control of the disease is paramount. The outcome of treatment of thyrotoxicosis using radioiodine shows variable failure rates depending, amongst other things, on the administered activity of radioiodine and the use of anti-thyroid drugs. Thus, management should follow an evidence based protocol, which has a low failure rate. METHOD: We prospectively analysed the outcome of treatment using our Gateshead protocol of a fixed administered activity of radioiodine therapy (400 MBq) given to 201 patients (including 140 with Graves' disease, 48 with toxic multinodular goitre (TMNG) and 13 with toxic nodule) followed up for a median period of 12 months (range, 6-77 months). Carbimazole was discontinued in patients rendered euthyroid 16 days prior to radioiodine. No routine anti-thyroid drugs or thyroxine were given following radioiodine unless hypothyroidism or thyrotoxicosis occurred. RESULTS: Following the Gateshead protocol led to a failure rate of 6.5% (eight females with Graves' disease, four females with TMNG and one female with toxic nodule), 29% euthyroidism and 64% hypothyroidism. The rates of hypothyroidism for women and for men were: in Graves' disease 77% and 79%, in TMNG 29% and 75%, in toxic nodule 42% and 0%, respectively. CONCLUSIONS: Our observations show that withholding an antithyroid drug in excess of just over 2 weeks prior to administering a fixed administered activity of radioiodine in patients with thyrotoxicosis leads to the lowest reported failure rate, irrespective of the underlying cause. One possible mechanism for this could be the avoidance of drug induced radio-resistance.     

Radioiodine treatment in patients with Graves' disease at outpatient clinic: special reference to safety and short-term outcome

PURPOSE: This retrospective study was aimed at revealing the safety and short-term outcome of radioiodine treatment in patients with Graves' disease at outpatient clinic. METHODS: From July 1999 to April 2002, 511 patients with Graves' disease were treated with radioiodine at the outpatient clinic of Tajiri Thyroid Clinic, Kumamoto. Of them, 73 patients dropped out or were referred to another medical institution. In the remaining 438 patients [100 men and 338 women; 44.6 +/- 15.4 (mean +/- SD) (14-82) years old], the safety of radioiodine treatment at the outpatient clinic and the treatment outcome until April 2003 was examined. The dosage was determined based on radioactive iodine uptake (3 hours) and thyroid volume measured by ultrasound. The initial dosage was 6.7 +/- 3.3 (1.2-13.5) mCi. Five months later, it was evaluated whether or not radioiodine should be administered a second time. All patients were treated at the outpatient clinic. RESULTS: There was no particular problem associated with treatment. Patients with a large goiter could be successfully treated with divided doses. After 12-45 (30.1 +/- 9.3) months of radioiodine, thyroid function status was as follows; hyperthyroidism: 7 patients (1.6%), subclinical hyperthyroidism: 78 patients (17.8%), euthyroidism: 108 patients (24.7%), subclinical hypothyroidism: 116 patients (26.5%), hypothyroidism: 129 patients (29.4%). CONCLUSION: It was concluded that radioiodine treatment in patients with Graves' disease at outpatient clinic was safe and showed a satisfactory short-term outcome.     

The evaluation of radioiodine therapy for thyroid patients using a fixed-dose regime

Ninety-six patients with toxic diffuse goitre (Grave's disease) in whom rapid control of disease was necessary were treated with an "ablative" dose of 550 MBq of radioiodine (131I) with the intention of inducing hypothyroidism. Outcome was established in 93 cases (mean follow-up 37 months), 45 patients (48%) becoming hypothyroid, 30 (32%) remaining euthyroid and 18 (19%) with persistent thyrotoxicosis requiring further 131I therapy. It is thus apparent that a fixed dose of 550 MBq 131I cannot be considered ablative, with less than 50% of patients developing hypothyroidism.     

Health effects of therapeutic use of 131I in hyperthyroidism.

Since 1942, therapy with radioiodine (Na131I) has gained a major role in the treatment of benign thyroid disorders, notably hyperthyroidism caused by Graves' disease or toxic multinodular goiter. The very large series of patients treated so far offer the opportunity for an assessment of both benign and malignant side effects. Hyperthyroidism is sometimes observed after radioiodine therapy due to radiation induced thyroid hormone or by an immunological mechanism. Despite the numerous attempts to design dosage schedules aiming at euthyroidism, hypothyroidism occurs in the majority of patients throughout life. Transient hypothyroidism may be observed within the first year after therapy and is caused by an immunological mechanism. Radioiodine therapy in Graves' disease may induce or worsen ophthalmopathy, which can be prevented by steroids effectively. Hypoparathyroidism and hyperparathyroidism have been reported after radioiodine therapy but probably do not exceed the normal incidence. Sialitis is commonly observed but mostly in patients treated with radioiodine for thyroid cancer. There are no indications for induction of genetic abnormalities after radioiodine therapy although no definite conclusion can be reached. Much attention has been paid to malignant disease. In very large series, no effects of radioiodine therapy on survival have been observed. Some studies report an increased relative risk for certain types of cancer (notably thyroid cancer, stomach cancer, bladder and kidney cancer or hematological malignancies). However, these observations were not confirmed by other large studies, so that no definite conclusion with respect to risk for certain types of malignant disease can be drawn. However, radioiodine therapy for benign thyroid disorders has generally been considered safe and without major side effects, hypothyroidism being the most frequent one.     

Graves病动脉栓塞治疗并发症分析

目的探讨甲状腺动脉栓塞治疗Graves病的并发症及其产生因素。方法对28例Graves病患者的甲状腺动脉造影、介入栓塞治疗、并发症及其产生因素进行分析,并作中期随访。结果1年有效率78.6%(治愈 好转),复发率14.2%。脑梗死2例(7.1%),1例治疗后恢复,1例并发甲状腺功能亢进危象抢救无效死亡;1例术后有一过性甲状腺功能减退,1例术后发生一过性甲状旁腺功能减退,无永久性的甲状腺和甲状旁腺功能减退;1例术后有较重的栓塞后综合征反应。其余并发症均经治疗后消失,随访至少1年以上,无其他不良反应。结论反流误栓是甲状腺动脉栓塞术治疗Graves病并发症产生的重要原因,栓塞时必须作超选插管、避开危险吻合、防止反流误拴,严格透视下操作,以期降低并发症、提高疗效。     

Graves' ophthalmopathy and 131I therapy.

Graves' ophthalmopathy is an autoimmune process initiated and maintained by antigen(s) shared by the thyroid and the orbit. A matter of argument concerns the choice of the method of treatment for Graves' hyperthyroidism when clinically evident ophthalmopathy is present. Restoration of euthyroidism appears to be beneficial for ophthalmopathy. On the other hand the continuing disease activity associated with the recurrence of hyperthyroidism appears to adversely affect the course of ophthalmopathy. For these reasons it is our opinion that in patients with Graves' hyperthyroidism and ophthalmopathy the permanent control of thyroid hyperfunction by ablation of thyroid tissue should be obtained by radioiodine therapy or thyroidectomy. The rationale for an ablative strategy is the following: i) permanent control of hyperthyroidism avoids exacerbations of eye disease associated with recurrence of hyperthyroidism; ii) hypothyroidism, which follows thyroid tissue ablation, should be regarded as a therapeutic end point rather than as an undesirable result; iii) ablation of thyroid tissue may result in the removal of both the thyroid-orbit cross-reacting antigen(s) and the major source of thyroid-autoreactive lymphocytes. The relationship between radioiodine therapy and the course of GO is a matter of controversy, and some authors have suggested that radioiodine administration may be associated with a worsening of preexisting ophthalmopathy. This was not observed when radioiodine treatment was associated with a 3-month oral course of prednisone. The development or progression of GO after radioiodine therapy might be due to the release of thyroid antigens following radiation injury and to subsequent exacerbations of autoimmune reactions directed towards antigens shared by the thyroid and the orbit. The view that radioiodine therapy may be associated with a progression of ophthalmopathy is not shared by some authors who claim that the apparent link between progression of ophthalmopathy and radioiodine therapy might simply be coincidental, reflecting the natural history of the disease. The radioiodine-associated exacerbation of eye disease might be used as an argument against the use of radioiodine therapy in patients with ophthalmopathy. We do not share this view, since the outward effects of radioiodine on eye disease can easily be prevented by concomitant administration of glucocorticoids. Glucocorticoid treatment should be limited, in our opinion, to patients with clinically evident eye disease and to those without ophthalmopathy but with other known risk factors, such as smoking.     

Graves' disease nd toxic nodular goiter--radioiodine therapy

At the 15th conference on the human thyroid in Heidelberg in 2001 the following aspects of the radioiodine therapy of benign thyroid disorders were presented: General strategies for therapy of benign thyroid diseases, criterions for conservative or definitive treatment of hyperthyroidism as first line therapy and finally preparation, procedural details, results, side effects, costs and follow-up care of radioiodine therapy as well as legal guidelines for hospitalization in Germany. The diagnosis Graves' hyperthyroidism needs the decision, if rather a conservative treatment or if primary radioiodine therapy is the best therapeutic approach. In the USA 70-90% of these patients are treated with radioiodine as first line therapy, whereas in Germany the conservative therapy for 1-1.5 years is recommended for 90%. This review describes subgroups of patients with Graves' disease showing a higher probability to relapse after conservative treatment. Comparing benefits, adverse effects, costs, and conveniences of both treatment strategies the authors conclude that radioiodine therapy should be preferred as first line therapy in 60-70% of the patients with Graves' hyperthyroidism.     

Iodine-131 uptake and turnover rate vary over short intervals in Graves' disease

From a Dutch questionnaire, it was apparent that nearly all institutions used percentage of radioiodine uptake for calculation of the radioiodine dose in Graves' disease. Although there is a general belief that fluctuations in radioiodine uptake may occur, with few exceptions relatively long intervals were accepted between the uptake measurement and the actual therapy dose. With the aim of optimizing the pretherapeutic work-up, we evaluated the stability of iodine uptake over time in patients with Graves' disease who were referred for 131I therapy. 131I uptake was measured in 300 consecutive patients for the calculation of the required 131I therapy dose; data were complete for 291 patients (97%). After discontinuing thyroid medication for 3 days, standardized thyroid probe measurements were performed 5 and 24 h after ingestion of a capsule containing 0.37 MBq 131I-NaI. Measurements were performed at the time of scintigraphic diagnosis (test 1), as well as immediately before 131I therapy (test 2). The time interval between test 1 and test 2 ranged from 2 to 421 (median 40) days. A relative increase or decrease greater than 10% between tests 1 and 2 occurred in 180 of 291 cases (62%) at 5 h and in 158 of 291 patients (54%) at 24 h. These changes were not related to the interval between the tests or to initial uptake values, thyroid mass, gender or age. Rapid turnover of radioiodine (5 h/24 h uptake ratio > 1) was noted in 17% of the patients during test 1 and in 15% during test 2. Rapid turnover was persistent (present in both tests 1 and 2) in only 9%. We conclude that patients with Graves' disease show considerable changes in 131I uptake over relatively short periods of time, and the turnover rate of 131I in this condition is not constant.     

265例精细个体化131I治疗Graves甲亢的疗效观察

目的 观察265例Graves甲亢患者精细个体化131I治疗后的疗效。 方法 回顾性分析265例应用131I治疗的Graves甲亢患者的临床资料,引入精细个体化治疗方案矫正系数,根据甲状腺大小、最高吸碘率、是否为毒性结节性或毒性弥漫性甲状腺肿等指标对矫正系数进行精细化,进而调整服131I的剂量,跟踪随访至少6个月。 结果 服药后3个月、6个月患者临床症状显著改善,TSH、血清游离三碘甲腺原氨酸、血清游离甲状腺素较治疗前明显降低,131I治疗后3个月和6个月的有效率分别为63.4%和81.5%,甲减率分别为24.9%和27.9%。 结论 精细个体化131I治疗Graves甲亢能够明显改善患者的临床症状,具有比较可靠的治疗效果。     

131I治疗青少年及儿童格雷夫斯甲亢的临床应用随访研究

目的探讨131I治疗青少年及儿童格雷夫斯甲状腺功能亢进症（Graves甲亢）的疗效及安全性。方法89例青少年及儿童Graves甲亢患者行131I治疗。给药剂量采用公式法计算（2.59~4.44 MBq/g）,参考病程、甲状腺质量和最高摄碘率进行修正。均采用一次性空腹口服,有合并症的给予相应处理。治疗后3、6、12个月随访,以后每年随访1次。前瞻性随访观察所有患者131I治疗后的治愈率、甲减率、甲状腺良恶性肿瘤发生情况、生长发育情况及后代健康情况。结果随访至今的患者共80例,失访9例（10.1%）。131I治疗剂量范围为177.6~555.0 MBq,平均剂量为203.5 MBq。随访至12个月,131I治疗青少年及儿童Graves甲亢痊愈率82.50%,有效率98.75%,无效率1.25%;随着时间的推移甲减发生率逐渐升高,15年甲减累计发生率为35%。所有治疗患者生长发育均正常,均育有后代,后代智力及发育均正常。随访病例中无甲状腺癌、白血病等疾病发生。结论131I治疗青少年及儿童Graves甲亢安全且疗效好,不良反应少,值得临床推广应用。     

The present status of I-131 therapy for Graves' hyperthyroidism in Japan (survey by questionnaire)

A survey on the I-131 therapy of Graves' hyperthyroidism was undertaken by questionnaire in 1,246 hospitals of Japan. One thousand and ninety seven of them (88.0%) responded to the questionnaire. In this paper, we report the results and analysis of the replies to the questionnaire. In the 121 hospitals (11.03%) of the respondents, I-131 therapy is being performed for Graves' hyperthyroidism. A gradual increase was observed in the annual number of I-131 treated Graves' disease patients during the period of 1998-2001, from 1,740 to 2,484. I-131 treatment was selected mainly for the cases with side effects from antithyroid drug (ATD) therapy, followed by the cases with complication of heart or hepatic diseases, recurrences of hyperthyroidism after surgery, radioiodine treatment, and long-term ATD treatment. The 41% of respondents used I-131 in order to restore euthyroidism, 34% aimed for hyperthyroidism and 41% used the dose properly between the two according to the patients. Administration dosage of I-131 was estimated mainly on the basis of thyroid uptake and volume in 93% of the respondents and 48% calculated the radiation dose by also determining the effective half-life in the thyroid gland. Thyroid size was estimated by scintigram (51%), US (33%), CT (22%) and palpation (12%). ATD treatment was used before I-131 administration by 70% of the respondents and 34% after radioiodine therapy. A low-iodine diet was given to the patients for a week (46%) or two weeks (47%) before I-131 administration. However, after treatment only 46% of the respondents continued low-iodine diet for a week.