Radioiodine treatment of Graves' disease. An assessment of its potential risks

Radioiodine therapy of thyrotoxicosis in children and adolescents. Indications, efficacy and safety. Literature review

Болезнь Грейвса (БГ) – основная причина тиреотоксикоза у детей. В современной клинической практике применяется три метода лечения БГ: тиреостатики, радиоактивный йод и операция. Все эти методы лечения применяются давно, и в мире накоплен огромный опыт применения каждого из методов лечения. Лечение начинают практически всегда с тиреостатиков, непереносимость или неэффективность которых становится показанием к выбору альтернативных методов лечения. Для осознанного выбора метода лечения необходимо понимать его потенциальные параметры эффективности и безопасности, а также влияющие на них факторы. Цель обзора – критический анализ эффективности и безопасности радиойодтерапии в лечении тиреотоксикоза у детей и подростков в сравнении с аналогичными показателями других методов лечения, а также показания и противопоказания к данному виду лечения в современной клинической практике эндокринологов, радиологов и эндокринных хирургов. Выбор тактики лечения БГ у ребенка на каждом этапе осуществляется согласованно с ним и его родителями/опекунами путем информирования лечащим врачом об объективных преимуществах и недостатках методов лечения на основе имеющейся доказательной базы. Также приведены основные рекомендации эффективной и безопасной терапии радиоактивным йодом БГ у детей и подростков.

Controversies in the management of Graves' disease in children

Graves' disease (GD) is the most prevalent cause of thyrotoxicosis in children. Because spontaneous and lasting resolution of this condition occurs in only a minority of patients, most pediatric patients with GD will need radioactive iodine treatment (¹³¹I) or thyroidectomy. Whereas the medication propylthiouracil (PTU) had been used in the past, only methimazole (MMI) should be now used in children, as PTU is associated with an unacceptable risk of liver failure. However, MMI may be associated minor and major side effects, which may be minimized using lower doses. An area of controversy involves the optimal duration of antithyroid drug (ATD) therapy. For some children, the prolonged use of antithyroid drugs is a valid approach, but for most, this will not increase the chance of remission. When ¹³¹I is administered, dosages should be greater than 150 uCi/gm of thyroid tissue, with higher dosages needed for larger glands. Considering that there will be low-level whole body radiation exposure associated with ¹³¹I, this treatment is viewed as controversial by some and should be avoided in young children. When surgery is performed, near-total or total thyroidectomy is the recommended procedure. Complications for thyroidectomy in children are considerably higher than in adults. Thus, an experienced thyroid surgeon is needed when children have surgery. Overall, when different treatment options for GD are considered, the benefits, risks and viewpoints of the family need to be considered and discussed in full.

Change in Practice over Four Decades in the Management of Graves' Disease in Scotland

There is continuing debate on the optimal treatment for Grave's thyrotoxicosis with a resultant variation in clinical practice. The present study aimed to ascertain changes in practice in the treatment of Grave's thyrotoxicosis in Tayside, Scotland, over the past four decades. Methods. The “Scottish automated follow-up register” (SAFUR) was queried to identify all patients treated for Grave's thyrotoxicosis from 1968 to 2007 inclusive. Patients were divided into 4 groups (Groups A to D) according to the decades. Demographic profile, treatment modalities, radioactive iodine (RAI) dose, and recurrence rates were studied and outcomes were compared by χ² test and ANOVA using SPSS v15.0. A p value of < 0.05 was considered significant. Results. Altogether, 3737 patients were diagnosed with Grave's thyrotoxicosis over the 4 decades. Use of RAI has increased from 43.1% in Group A to 68% in Group D (p < 0.001). The dose of RAI has increased (p < 0.001) and there has been a reduction in recurrence rate with higher dose of RAI. Surgical intervention rates decreased from 55.3% to 12.3% (p < 0.001) over time. Conclusions. Analysis of a large dataset of patients with Grave's thyrotoxicosis suggests increasing use of RAI as the preferred first line of treatment. Furthermore, using a single higher dose of RAI and adoption of total thyroidectomy have decreased recurrence rates.

Pediatric Graves' disease: management in the post-propylthiouracil Era

The most prevalent cause of thyrotoxicosis in children is Graves’ disease (GD), and remission occurs only in a modest proportion of patients. Thus most pediatric patients with GD will need treatment with radioactive iodine (RAI; ¹³¹I) or surgical thyroidectomy. When antithyroid drugs (ATDs) are prescribed, only methimazole (MMI) should be administered, as PTU is associated with an unacceptable risk of severe liver injury. If remission does not occur following ATD therapy, ¹³¹I or surgery should be contemplated. When ¹³¹I is administered, dosages should be greater than 150 uCi/gm of thyroid tissue, with higher dosages needed for large glands. Considering that there will be low-level whole body radiation exposure associated with ¹³¹I, this treatment should be avoided in young children. When surgery is performed near total or total-thyroidectomy is the recommended procedure. Complications for thyroidectomy in children are considerably higher than in adults, thus an experienced thyroid surgeon is needed when children are operated on. Most importantly, the care of children with GD can be complicated and requires physicians with expertise in the area.

Radioactive iodine (131I) therapy for differentiated thyroid cancer in Japan: current issues with historical review and future perspective

Radioactive iodine (RAI, (131)I) has been used as a therapeutic agent for differentiated thyroid cancer (DTC) with over 50 years of history. Recently, it is now attracting attention in medical fields as one of the molecular targeting therapies, which is known as targeted radionuclide therapy. Radioactive iodine therapy (RIT) for DTC, however, is now at stake in Japan, because Japan is confronting several problems, including the recent occurrence of the Great East Japan Disaster (GEJD) in March 2011. RIT for DTC is strictly limited in Japan and requires hospitalization. Because of strict regulations, severe lack of medical facilities for RIT has become one of the most important medical problems, which results in prolonged waiting time for Japanese patients with DTC, including those with distant metastasis, who wish to receive RIT immediately. This situation is also due to various other factors, such as prolonged economic recession, super-aging society, and subsequent rapidly changing medical environment. In addition, due to the experience of atomic bombings in Hiroshima and Nagasaki, Japanese people have strong feeling of "radiophobia". There is fear that GEJD and related radiation contamination may worsen this feeling, which might be reflected in more severe regulation of RIT. To overcome these difficulties, it is essential to collect and disclose all information about the circumstances around this therapy in Japan. In this review, we would like to look at this therapy through several lenses, including historical, cultural, medical, and socio-economic points of view. We believe that clarifying the problems is sure to lead to the resolution of this complicated situation. We have also included several recommendations for future improvements.

Current concepts in graves' disease

Graves' disease is the most common cause of hyperthyroidism in the developed world. It is caused by an immune defect in genetically susceptible individuals in whom the production of unique antibodies results in thyroid hormone excess and glandular hyperplasia. When unrecognized, Graves' disease impacts negatively on quality of life and poses serious risks of psychosis, tachyarrhythmia and cardiac failure. Beyond the thyroid, Graves' disease has diverse soft-tissue effects that reflect its systemic autoimmune nature. Thyroid eye disease is the most common of these manifestations and is important to recognise given its risk to vision and potential to deteriorate in response to radioactive iodine ablation. In this review we discuss the investigation and management of Graves' disease, the recent controversy regarding the hepatotoxicity of propylthiouracil and the emergence of novel small-molecule thyroid-stimulating hormone (TSH) receptor ligands as potential targets in the treatment of Graves' disease.

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.

The treatment of Graves' disease in children

Graves' disease is the most common form of hyperthyroidism in childhood. Current treatment options include antithyroid medications, surgery, and radioactive iodine. Medical therapy is generally associated with long-term remission rates of less than 25% and a small risk of serious adverse reactions that include hepatic failure and bone marrow suppression. Total thyroidectomy is associated with very high cure rates and a small risk of hypoparathyroidism and recurrent laryngeal nerve damage. When radioactive iodine is used at appropriate doses, there is a very high cure rate without increased risks of thyroid cancer or genetic damage. Clinicians caring for the child or adolescent with Graves' disease are thus faced with using medications with potential short-term and long-term toxicity, for a condition in which spontaneous remission occurs in the minority of pediatric patients. Definitive therapy in the form of surgery or radioactive iodine is necessary and unavoidable for the majority of pediatric patients with Graves' disease.

Optimisation of thyroid hormone replacement using an automated thyroid register

The high prevalence of thyroid dysfunction requires an efficient and effective means of monitoring and adjustment. We compared the current network of 12,524 patients with thyroid dysfunction with register data prior to 1991 to examine the precision of thyroxine replacement in patients with hypothyroidism and assess locally changing trends in treatment of hyperthyroidism. Since 1991, due to the associated adverse effects of a suppressed thyroid-stimulating hormone (TSH) (<0.03 mU/l), the network has facilitated a significant reduction in the proportion of thyroxine-treated patients with TSH suppression from 58.5% before 1991 to 9.2 +/- 3.8% thereafter. Since 1991, there has been an increased use of radioiodine by 14.3% [95% confidence interval (95% CI): 10.6-17.8] and a reduced use of thyroidectomy by 12.3% (95% CI: 8.8-15.8) to treat hyperthyroid patients compared with before 1991. Between the two treatments, there were no differences in subsequent rates of hypothyroidism or mean thyroxine dosage.

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.

5: Diagnosis and management of hyperthyroidism and hypothyroidism

The most common cause of hyperthyroidism in Australia is Graves disease, caused by a defect in immunoregulation in genetically predisposed individuals, leading to production of thyroid-stimulating antibodies. Each of the three modalities of therapy for Graves disease--thionamide drugs, subtotal or total thyroidectomy, and radioactive iodine ablation--can render the patient euthyroid, but all have potential adverse effects and may not eliminate recurrences. Hypothyroidism occurs in about 5% of the adult population; most present with "subclinical" hypothyroidism (mild thyroid failure), characterised by raised levels of serum thyroid stimulating hormone (TSH) but normal free thyroxine (T(4)). The most common cause of hypothyroidism in Australia is autoimmune chronic lymphocytic thyroiditis, characterised by raised circulating levels of thyroid peroxidase antibody. Symptoms and signs of hypothyroidism are often mild or subtle and, when there is clinical suspicion, thyroid function tests are needed; if serum TSH level is raised, free T(4) and thyroid peroxidase antibody should be measured. Replacement therapy with thyroxine is the cornerstone of therapy (1.6 microg/kg lean body weight daily, taken on an empty stomach); combination therapy with thyroxine and liothyronine (T(3)) is promoted, but there is little evidence of its clinical benefit. Despite the development of highly sensitive laboratory tests, clinical assessment and judgement remain paramount

Utilização do 131I no tratamento da doença de Basedow-Graves na infância e adolescência

Embora o diagnóstico da Doença de Graves (DG) na infância e adolescência seja relativamente fácil, seu tratamento ainda é controverso. Pode-se utilizar fármacos anti-tireoideanos (MMZ ou PTU), porém a incidência de efeitos adversos nessa faixa etária é maior que nos adultos e a taxa de remissão é baixa, mesmo com o uso prolongado. A cirurgia é pouco indicada como tratamento inicial, sendo realizada mais freqüentemente após recidiva do tratamento medicamentoso e/ou devido aos seus efeitos adversos. A utilização da radioiodoterapia na infância e adolescência vem crescendo. Com doses adequadas, ocorre o desenvolvimento de hipotireoidismo em cerca de 90% dos casos num período de 3 a 6 meses. Os dados iniciais sugerem que o tratamento em crianças acima de 5 anos não parece estar associado a maior risco de carcinoma de tireóide. A prevalência de efeitos adversos é menor que na cirurgia. Pacientes que apresentam fatores clínicos ou laboratoriais de pior prognóstico evolutivo podem ter seu tratamento medicamentoso encurtado, sendo a indicação da radioiodoterapia realizada mais precocemente.

Iodo radioativo no manejo do hipertireoidismo da doença de Graves

O hipertireoidismo da doença de Graves, a forma mais comum de hipertireoidismo, é diretamente causado por auto-anticorpos que ativam o receptor do TSH. A etiologia parece ser multifatorial, envolvendo fatores genéticos e não genéticos. As opções terapêuticas atualmente disponíveis são as drogas antitireoidianas (DAT), a cirurgia e o iodo radioativo (131I), sendo que nenhuma delas é considerada ideal, visto que não atuam diretamente na etiologia/patogênese da disfunção. O 131I tem sido cada vez mais utilizado como primeira escolha terapêutica por tratar-se de um tratamento definitivo, de fácil administração e seguro. A associação com DAT, fatores prognósticos de falência e o cálculo da dose administrada são alguns dos aspectos controversos na utilização do 131I, sendo este o principal foco desta revisão. As DAT ainda são utilizadas como primeira escolha nos casos de pacientes com bócios pequenos, crianças e adolescentes, e na gravidez. A tireoidectomia é, atualmente, quase um tratamento de exceção, com indicação restrita para casos em que as DAT ou o 131I sejam contra-indicados.

Graves disease in childhood: a review of the options for diagnosis and treatment

While diagnosing Graves disease in childhood and adolescence does not usually present specific problems, the treatment of hyperthyroidism is still controversial. In particular, with regard to the use of radioiodine therapy, strategies vary between many European and North American pediatric endocrinology centers. After the diagnosis is made, antithyroid drug treatment with methimazole (thiamazole), carbimazole, or propylthiouracil should be performed with caution, in particular, because of severe adverse effects, such as agranulocytosis or hepatitis, that are found in up to 1% of patients. Antithyroid drug treatment should not be continued long-term, particularly since definitive remission cannot be expected in more than 30-40% of patients. In contrast, the risk of severe adverse effects is still present, and the risk of thyroid carcinoma increases with time and appears to be considerably higher than after radioiodine treatment. To a great extent, the success of surgery depends on the skills of a trained surgeon. The question of whether to perform total or subtotal thyroidectomy is yet to be resolved. Surgery should be considered in patients with a large thyroid gland (>80g), severe ophthalmopathy, and a lack of remission on antithyroid drug treatment. Success rates have increased to up to 97%, while severe adverse effects (laryngeal nerve palsy, hypoparathyroidism) occur in approximately 4% of patients. Mortality is below 0.1%. Radioiodine treatment in children >5 years of age does not appear to be associated with an increased risk of thyroid carcinoma; however, long-term data are lacking. Compared with the surgical approach, success rates are lower, particularly if low doses of radioiodine are used. In general, adverse effects are less prevalent than in patients who have undergone surgery.

Tratamento do hipertireoidismo da Doença de Graves

A Doença de Graves constitui a forma mais comum de hipertireoidismo e três abordagens terapêuticas são atualmente utilizadas: drogas antitireoidianas (DAT), cirurgia e iodo radioativo (131I). As DAT continuam como tratamento de primeira escolha em pacientes com doença leve, bócios pequenos, crianças e adolescentes, e em situações especiais como na gravidez. Por outro lado, o 131I tem sido cada vez mais utilizado, porque é considerado um tratamento seguro, definitivo e de fácil aplicação. O risco de exacerbação do hipertireoidismo após administração do 131I, os fatores prognósticos de falência e o cálculo da dose administrada têm sido alguns dos aspectos discutidos na literatura recentemente, e são particulamente comentados nesta revisão. O tratamento cirúrgico constitui quase um tratamento de exceção, com indicação para os casos em que as terapias anteriores não possam ser utilizadas.

Treatment of Graves' disease: the advantages of surgery

The authors and others believe that surgery (thyroidectomy) is underused in the treatment for patients with Graves' disease. It is the most rapid and consistent method of making the patient euthyroid; it avoids the possible long-term risks of radioactive iodine; and it provides tissue for histologic examination. Children, young women, pregnant women, and patients with coexistent thyroid nodules are ideal candidates for thyroidectomy. It also is the treatment of choice for patients with Graves' ophthalmopathy. Patients should be rendered euthyroid before thyroidectomy. Although the operation is technically more difficult than operating on patients with nontoxic goiter or thyroid neoplasms because of the vascularity of the thyroid gland, this difference is small, and the complication rates are low. The authors recommend the Hartley-Dunhill operation (total thyroidectomy on one side and subtotal thyroidectomy on the other side, leaving about 4 to 5 g of thyroid tissue) for most patients and total thyroidectomy for patients with Graves' ophthalmopathy. In patients with recurrent or persistent thyroid cancer who fail to respond to surgery and radioactive iodine ablation, immunosuppressive therapy should be considered.

Outcome of pregnancy after radioactive iodine treatment for well differentiated thyroid carcinomas

This study sought to determine the outcome of pregnancy in female patients with differentiated thyroid carcinoma who became pregnant after radioactive iodide treatment. A total of 779 female thyroid cancer patients were treated at Chang Gung Medical Center in Linkou between January 1977 and December 1995. The medical records of these patients were reviewed retrospectively. Thirty-seven of these patients had well differentiated thyroid carcinoma receiving 131I treatment and conceived at a mean age of 27.97 +/- 3.49 year-old. A total of 58 pregnancy episodes were recorded during this study period. Among these 37 patients, 3 episodes of artificial abortion, 8 episodes of spontaneous abortion and 2 threatened abortions were observed. These patients delivered a total of 47 babies including 3 premature babies. Seven of these patients conceived within 6 months after the last administration of 131I, including 2 cases within 1 month, 4 cases within 4 months, and 1 patient within 5 months. Of these 7 patients, only one patient who conceived within 6 months after the last administration of 131I (14.3%) had a spontaneous abortion. The present results suggest that previous administration of 131I in female patients with well differentiated thyroid cancer does not result in demonstrable adverse effects in subsequent pregnancies. However, further studies involving long-term follow-up of children delivered by mothers who became pregnant within 6 months after the last administration of 131I is needed to further elucidate the possible chronic effects and sequelae of 131I therapy on subsequent pregnancies.

Radioiodine treatment in unsuspected pregnancy

OBJECTIVE

Radioiodine is being used increasingly as first line therapy for hyperthyroidism. Our aim is to highlight some of the difficulties which can occur following the use of 131I to treat hyperthyroidism in fertile women.

PATIENTS

We present 3 cases of young women to whom radioiodine was given, only to find some weeks later that they had been pregnant at the time of treatment.

CONCLUSIONS

These cases serve as a reminder of the importance of obtaining an accurate and full menstrual and contraceptive history. Guidelines advocate the application of the ten day rule with the further recommendation that pregnancy testing may be undertaken as an alternative.

Treatment of hyperthyroidism with radioactive iodine

Treatment of hyperthyroidism with RAI has been performed for more than a half century with efficacy and safety. For its optimal use, the physician must employ appropriate patient selection criteria and clinical judgment concerning pretreatment patient preparation. The dose of the 131I needed remains an area of uncertainty and debate; thus far, it has not been possible to resolve the trade-off between efficient definitive cure of hyperthyroidism and the high incidence of post-therapy hypothyroidism. Early side effects are uncommon and readily manageable. Other than the need for long-term monitoring and, in most cases, lifelong L-T4 treatment, late adverse consequences of this treatment remain only conjectural. The available follow-up studies support the current majority opinion of North American thyroid specialists that RAI treatment is an excellent choice for most hyperthyroid patients.

Role of thyroid-stimulating blocking antibody in patients who developed hypothyroidism within one year after 131I treatment for Graves' disease

OBJECTIVE

We recently reported that thyroid-stimulating blocking antibody (TSBAb) may not contribute to the development of hypothyroidism more than six years after 131I treatment. In the present study, we attempted to determine whether hypothyroidism that develops within a shorter period of time following 131I therapy is associated with TSBAb.

DESIGN

Retrospective study.

PATIENTS

Sera were obtained from 8 patients who developed hypothyroidism within 6 months after 131I therapy (Group 1), 8 patients who became euthyroid one year after 131I therapy (Group 2), and 7 patients who developed transient hypothyroidism (Group 3).

MEASUREMENTS

Thyroid stimulating antibody (TSAb) activity was measured as the amount of cyclic adenosine monophosphate (cAMP) produced by cultured FRTL-5 cells, and TSBAb activity as the inhibition of cAMP produced in response to 100 mU/l bovine TSH.

RESULTS

At about 3 months after 131I treatment, TSAb activity increased significantly in Groups 2 and 3, but did not change in Group 1. In contrast, TSBAb activity in Group 1 increased significantly and was positive in 6 patients at that time. At 12-18 months after 131I treatment, TSBAb activity tended to decrease and remained positive in 3 patients but became negative in 3 patients. It did not change in the patients in Groups 2 and 3. The patients in Group 1 were treated with levothyroxine, 75-125 micrograms/day. Levothyroxine was discontinued in the 3 patients whose TSBAb activity disappeared. Two of them remained euthyroid, and 1 became hypothyroid.

CONCLUSION

Results indicate that the hypothyroidism that develops within a short time after 131I treatment may be caused by TSBAb activity. Thyroid function may be recovered when TSBAb activity disappears.

Thyroid disease in women

Thyroid diseases occur more commonly in women than men, in part because of the autoimmune nature of many thyroid disorders. Hypothyroidism, and thyroid nodules occur frequently in both pre- and postmenopausal women. Pregnancy is also associated with changes in thyroid function. The goal of this article is to review the current information on the pathophysiology and treatment of thyroid disorders which are common in women.

Treatment of Graves' disease: the American way

The treatment of patients with Graves' disease involves a physician making a clinical decision between one of the three modalities available for treatment, administering the treatment and following the patients. There appears to be a difference in treatment bias for treating the 'average' patient with Graves' disease, with American physicians preferring radioactive iodine while their European and Japanese cohorts prefer long-term anti-thyroid drugs. There are no facts to support this bias. The treating physician usually makes the decision based on his or her preference. In addition, American physicians are under pressure to prescribe the most cost-effective therapy, leading to an even stronger bias towards radioactive iodine.

Total thyroidectomy for Graves' disease

BACKGROUND

Therapeutic options for treatment of hyperthyroidism caused by Graves' disease remain controversial. There are three main options: thiourea drugs, radioactive iodine ablation, and thyroidectomy. Each treatment has significant advantages and potential problems.

METHODS

The present study is a retrospective analysis of our experience with total thyroidectomy in Graves' disease. Sixty-two patients underwent this procedure in 11 years' time and were followed for a minimum of 2 years after surgery. All had measurement of total thyroxine, T3 uptake, and radioactive iodine (RAI) uptake and scanning. Sixty-three percent of all patients had some element of hyperthyroid eye signs. All patients were rendered euthyroid with pharmacologic therapy prior to surgery. Postoperatively, the patients were evaluated for improvement in eye signs, incidence of recurrent laryngeal nerve injury, and hypoparathyroidism.

RESULTS

None of the patients in this study have developed recurrent hyperthyroidism. All patients are maintained on levothyroxine. None of our patients incurred bilateral vocal cord paralysis. One patient (1.6%) demonstrated an immobile vocal cord more than 1 year following surgery. Ten patients (16%) demonstrated impaired mobility of one vocal cord in the immediate postoperative period. Nine of these patients recovered full vocal cord mobility within 6 months after surgery. Only one patient (1.6%) still required calcium and vitamin D therapy 1 year following surgery. However, in the immediate postoperative period, 23 patients (37%) required supplemental calcium and vitamin D. In 12 patients, calcium and vitamin D was discontinued within 1 month. In an additional 6 patients, calcium and vitamin D were discontinued within 4 months; 3 patients, within 6 months; and 1 patient, within 12 months after surgery. Incidental papillary carcinoma was found in 3 patients (5%).

CONCLUSIONS

Total thyroidectomy for Graves' disease is an effective and safe therapy. When performed by an experienced head and neck surgeon, it carries a low morbidity rate. It should be presented to patients as a therapeutic option within the context of a comprehensive discussion of the risks and benefits of radioactive iodine, pharmacologic therapy, and surgery.

Pattern of recovery of the hypothalamic-pituitary-thyroid axis following radioactive iodine therapy in patients with Graves' disease

PURPOSE

To characterize the time course of recovery of the hypothalamic-pituitary-thyroid (HPT) axis by determining the frequency, onset, duration, and clinical attributes of the central hypothyroid phase following 131I therapy for Graves' disease and to examine whether the central hypothyroid phase is due to direct pituitary thyrotroph suppression or to hypothalamic thyrotropin-releasing hormone (TRH) deficiency.

PATIENTS AND METHODS

Twenty-one hyperthyroid patients with Graves' disease evaluated at a university endocrine clinic and treated with radioactive iodine were prospectively studied. Serial thyroid function levels (serum thyroxine [T4], free thyroxine [free T4], triiodothyronine [T3], and thyroid-stimulating hormone [TSH]) were measured and TRH stimulation tests were performed at 2 to 4 week intervals for all subjects following 131I treatment. None of the patients was treated with thionamides after receiving 131I therapy.

RESULTS

Nineteen (90%) of the patients with Graves' disease experienced a transient central hypothyroid phase defined as the presence of a suppressed or inappropriately normal TSH level despite a low free T4 level following 131I treatment. This phase occurred a mean of 62.8 +/- 5.1 days following 131I treatment, persisted for an average of 24.7 +/- 2.4 days, and was not predictive of eventual treatment outcome. All patients had concordantly low T4 and T3 levels during this period and exhibited a blunted TSH response to TRH compared to 29 euthyroid control subjects, suggesting primary feedback suppression at the level of the pituitary thyrotrophs. The suppressed thyrotrophs required a minimum of 2 weeks to recover once patients became hypothyroid. The length of preexisting hyperthyroidism, basal free T4 elevation, and administered dose of 131I failed to predict the duration of the central hypothyroid phase, although a higher dose of 131I was associated with an earlier onset of central hypothyroidism (r = -.51, P < 0.05).

CONCLUSIONS

Clinicians should be aware of the delay in the recovery of the HPT axis that occurs in the majority of patients with Graves' disease treated with 131I and is manifested by a transient central hypothyroid phase. The blunted TSH response to TRH stimulation during this period suggests that suppression occurs primarily at the level of the pituitary thyrotrophs. The use of sensitive TSH measurements alone to monitor these patients during this period is not helpful and may be misleading.

A Clinical Guide to the Management of Graves’ Disease with Radioactive Iodine

More than 50 years have passed since radioactive iodine (RAI) was initially demonstrated as a therapeutic modality for the treatment of Graves' Disease. Today, more than a million patients have been treated with RAI. RAI is considered safe and highly effective. Its side-effect profile, ease of administration, and relative cost make RAI the treatment of choice for Graves' Disease of thyroidologists in this country. Questions continue to be raised as to which patients will benefit most from RAI therapy. Marked differences still exist between the practice preferences of thyroidologists as to whom, when, and how to treat with RAI. Factors that influence patient selection for RAI include age, the presence of pre-existing ophthalmopathy, lifestyle, history of previous treatment failure, and goiter size. Treatment goals, dosimetry, use of thionamides prior to therapy, safety recommendations following therapy, and prophylactic therapy with glucocorticoids for patients with ophthalmopathy highlight are some of the controversial issues facing the endocrinologist treating Graves' Disease with RAI. This symposium article reviews the current management of Graves' Disease with RAI.

Has the use of antithyroid drugs for Graves' disease become obsolete?

In spite of an experience of almost 50 years of use of antithyroid drugs and radioiodine for the treatment of Graves' disease, the rationale for choice is often obscure. Early reports of high remission rates during thiourea therapy were followed by less optimistic ones, which along with other factors may have fueled the current major shift toward use of radioiodine. This review examines whether or not the use of antithyroid drugs indeed may have become obsolete. The intrathyroidal and extrathyroidal mechanisms of action of the drugs are reviewed with emphasis on their potential immunosuppressive effects. The latter may involve a direct effect on thyroid follicular cells, a direct suppression of TSH receptor antibody formation, or indirect effects mediated via heat shock proteins, oxygen free radicals, and the immune system. Potential factors associated with success or failure with antithyroid drug therapy are discussed, such as the effects of dose and duration of treatment, iodine milieu, and concomitant L-thyroxine therapy. The risks inherent to radioiodine therapy are only briefly described with emphasis on the possible aggravation by radioiodine of preexistent ophthalmopathy. The reader must decide whether the evidence marshalled convincingly indicates that the use of the thiourea compounds should be abandoned. The author thinks not, and is optimistic that imminent discovery of the yet elusive and enigmatic pathogenesis of Graves' disease will permit new and innovative treatment or more effective use of currently available therapies.

Intervention in Graves' disease. Choosing among imperfect but effective treatment options

Graves' disease is an autoimmune disorder that comprises the triad of diffuse toxic goiter, ophthalmopathy, and infiltrative dermopathy, although all three are not necessarily present in a given patient. The manifestations of Graves' disease vary, depending on the patient's age and other factors. Choice of therapy is influenced by the patient's age, history of heart disease, pregnancy status, expectations, and preferences. Most patients are treated with either radioactive iodine (sodium iodide I 131 [Iodotope]) or the antithyroid drugs propylthiouracil or methimazole (Tapazole). Antithyroid drugs may be more effective in producing long-term remission if levothyroxine sodium (Levothroid, Levoxine, Synthroid) is added to the regimen after the patient becomes euthyroid. Hypothyroidism occurs in many patients following 131I therapy but is also seen in a substantial number of patients who have been treated with thyroidectomy and even in some who have taken antithyroid drugs. Long-term follow-up is necessary, regardless of type of initial treatment, and should include an annual physical examination and measurement of serum concentrations of thyrotropin and the free thyroxine index, both of which should be maintained in the normal range.

The effect of radioactive iodine treatment on thyroid C cells

To determine the effect of radioiodine treatment on thyroid C cells, calcitonin (CT) levels were measured by RIA before and after intravenous calcium stimulation (2 mg/kg body-weight elemental calcium) in 22 women treated with 131I for hyperthyroidism. The results were compared with sex, age and weight-matched normal controls. There was a slight but statistically significant decrease in basal CT levels of the patients compared to the control group (mean +/- SE; 0.009 +/- 0.001 vs 0.011 +/- 0.001 pmol/l, P less than 0.05). The mean stimulated CT level of the patient group was significantly lower than that of the controls (0.010 +/- 0.001 vs. 0.018 +/- 0.003 pmol/l, P less than 0.001). The absence or presence of 131I-induced hypothyroidism at the time of the study did not influence basal or stimulated CT levels. Basal and stimulated CT levels were significantly lower in the patients with Graves' disease than in the patients with toxic nodular goitre. We conclude that 131I used to correct hyperthyroidism may cause marked CT deficiency.

Unexplained weight loss in an elderly patient. Delayed diagnosis of thyrotoxicosis

Because the presenting symptoms of hyperthyroidism are often misleading in elderly patients, diagnosis depends on a high degree of clinical suspicion. The presence of unexplained weight loss, atrial fibrillation, or heart failure (especially in a patient without a history of heart problems) justifies testing for thyrotoxicosis.

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

The clinical outcome of 199 patients with Graves' disease treated with standardized 185MBq 131I therapy doses has been analysed. Most patients were controlled with antithyroid drugs prior to the 131I therapy, and also received antithyroid drugs for several months following 131I. The median follow-up period was 5.5 years. The single 185MBq 131I dose successfully treated 72.4% of patients. The 1, 2 and 5 year hypothyroid figures were 15.5%, 19.3% and 27.3%, respectively. Previous thyroidectomy was associated with an increased hypothyroid rate. Retreatment was required by 25.6%, with 3.5% requiring more than two 131I doses. Discriminant analysis of pretreatment variables suggests that patients with large goitres or severe disease (serum T3 greater than 10nmol/l) should be treated with higher doses of 131I.

Graves' disease. Manifestations and therapeutic options

Graves' disease is the most common cause of hyperthyroidism. Clinical features include thyroid enlargement, eye signs, tachycardia, heat intolerance, emotional lability, weight loss, and hyperkinesis. Three modes of therapy are available. The preferences of the patient and physician are usually prime considerations in devising the therapeutic plan. Radioactive iodine is the most frequently used and safest method of treatment for adults. Antithyroid drugs are preferred for children and pregnant women. Surgery is usually reserved for patients in whom the other forms of treatment are not acceptable. Considerable patient education during the decision-making process enhances the success of the therapeutic plan.