Radioyodo como tratamiento de hipertiroidismo en un paciente en hemodiálisis: Caso clínico / Treatment of hyperthyroidism with radioiodine during hemodialysis: Report of one case

Although radioiodine (131-I) can be used as treatment of hyperthyroidism for patients in hemodialysis, its use is limited and the experience is mainly related to differentiated thyroid carcinoma. We report a 58 years old female on hemodialysis with recurrent hyperthyroidism after propylthiouracil treatment. She was successfully treated with 131-I and four months after the intervention her euthyroid state was confirmed. We measured 131-I activity in blood, dialysate liquid and other waste products, as well as patient radiation exposure rates. We found that 131-I elimination was prolonged through time with no major dependence on hemodialysis, as opposed to the elimination of 131-I in patients with thyroid carcinoma. This was probably due to high radiotracer uptake in hyper functioning thyroid tissue. Conversely, radiation content in dialysate wastes or equipment was minimal. Furthermore, the rate of both environmental exposure and exposure of nursing staff in charge of hemodialysis sessions, was minimal and met international security standards. In conclusion, I-131 therapy showed both appropriate effectiveness and safety in this case and may be considered as a suitable treatment alternative to thyroidectomy when antithyroid drugs are unsuccessful.

Radioiodine therapy in elderly patients with subclinical hyperthyroidism due to non-voluminous nodular goiter and its effect on bone metabolism / Terapia com radioiodo em pacientes idosos com hipertireoidismo subclínico por bócio nodular não volumoso e efeito sobre o metabolismo ósseo

OBJECTIVE: To evaluate 131I therapy in elderly patients with subclinical hyperthyroidism (SCH) due to nodular disease and who did not receive antithyroid drugs (ATDs), and the effect of the treatment on bone metabolism. SUBJECTS AND METHODS: Thirty-six patients with TSH ≤ 0.1 mIU/L and non-voluminous goiter (< 60 cm³) were studied. Bone mineral density (BMD) was assessed in 17 women with osteopenia. RESULTS: Mean 24-h 131I uptake was 17.5%. Symptoms of thyrotoxicosis were reported by two (5.5%) patients in the first week after therapy. One year after radioiodine treatment, SCH was resolved in 30 (83.3%) patients, and hypothyroidism was detected in one (2.7%). In the patients in whom TSH returned to normal, femoral and lumbar spine BMD increased by 1.9% and 1.6%, respectively, in average. CONCLUSIONS: In elderly patients with SCH and non-voluminous goiter, radioiodine not preceded by ATDs is a safe and effective therapeutic alternative. Resolution of SCH has beneficial effects on BMD in postmenopausal women with osteopenia.

OBJETIVO: Avaliar a terapia com 131I em idosos com hipertireoidismo subclínico (HSC) por doença nodular que não receberam drogas antitireoidianas (DATs) e o efeito no metabolismo ósseo. SUJEITOS E MÉTODOS: Trinta e seis pacientes com TSH ≤ 0,1 mUI/L e bócio não volumoso (< 60 cm³) foram estudados. Dezessete mulheres com osteopenia foram submetidas à avaliação da densidade mineral óssea (DMO). RESULTADOS: Captação média de 131I em 24 h foi 17,5%. Sintomas de tireotoxicose foram reportados por dois pacientes (5,5%) na primeira semana após a terapia. Um ano após o radioiodo, HSC foi resolvido em 30 pacientes (83,3%) e hipotireoidismo ocorreu em 1 (2,7%). Nas pacientes que normalizaram o TSH, DMO em fêmur e coluna lombar incrementou em média 1,9% e 1,6%, respectivamente. CONCLUSÕES: Em idosos com HSC e bócio não volumoso, radioiodo, não precedido de DATs, é uma alternativa terapêutica segura e eficaz. Resolução do HSC tem benefício na DMO em mulheres menopausadas com osteopenia.

Correlação entre volume tireoidiano determinado pelo método de ultrassonografia versus cintilografia e sua implicação em cálculos dosimétricos na terapia com radioiodo na doença de Graves / Correlation between thyroid volume determined either by ultrasound or by scintigraphy and its implications in dosimetric radioiodine calculations in Graves disease treatment

INTRODUÇÃO: A doença de Graves (DG) é a causa mais comum de hipertireoidismo e, entre as abordagens terapêuticas mais utilizadas para o tratamento do hipertireoidismo por doença de Graves, encontram-se a cirurgia, o uso de drogas antitireoidianas e a radioiodoterapia. No cálculo dosimétrico para determinação da dose de radioiodo a ser utilizada, é possível empregar a ultrassonografia e a cintilografia para avaliar o volume tireoidiano. OBJETIVO: O presente estudo visa correlacionar essas metodologias com ênfase no volume obtido e nas implicações dosimétricas. SUJEITOS E MÉTODOS: Foram incluídos no estudo 103 pacientes com diagnóstico de DG encaminhados para radioiodoterapia. Esses foram submetidos à ultrassonografia da tireoide e à cintilografia tireoidiana, com cálculo de volume pela cintilografia baseado na fórmula de Allen. RESULTADOS E CONCLUSÕES: Observou-se boa correlação entre os dois métodos, porém com massa estimada pela cintilografia sistematicamente maior que a estimada pela ultrassonografia, o que pode acarretar em menor estimativa de dose absorvida quando utilizado o método cintilográfico.

INTRODUCTION: Graves disease (GD) is the most common cause of hiperthyroidism, and the most common treatment options are surgery, antithyroid drugs and radioiodine therapy. In radiodosimetric calculations to determine radioiodine dosage it is possible to use thyroid volume estimatives based on ultrasound or scintigraphy. OBJECTIVE: The present study aimed to correlate these methodologies emphasizing volume estimatives and dosimetric implications. SUBJECTS AND METHODS: Were included 103 patients with GD diagnosis and indication of radioiodine treatment. They were submitted to thyroid ultrasound and thyroid scintigraphy. RESULTS AND CONCLUSIONS: Good correlation between both methods was observed, although scintigraphy systematically obtained greater volumes than ultrasound implying in lower estimatives of absorbed dose when scintigraphy is used.

Transient cytotoxicity of 131I beta radiation in hyperthyroid patients treated with radioactive iodine.

Background & objectives: Radioiodine (131I) or radioactive iodine in low doses is used worldwide as the first line of management in the treatment of hyperthyroidism. Information is available on the extent and severity of cell damage after a high dose radioiodine (131I) therapy for thyroid cancer, but information is scanty on its cellular effects, its extent and severity of cell damage after a low dose 131I therapy. The present investigation was aimed to study the cytotoxic effects of a low dose 131I therapy in varying doses as is normally being used in routine clinical practice in the treatment of various forms of hyperthyroidism. Methods: Peripheral blood lymphocytes were analyzed in 32 hyperthyroid patients. All of them received 131I in the form of sodium iodide solution orally. Blood lymphocytes were studied for the presence of chromosomal aberrations (CA) and micro nucleus (MN) using micronucleus assay. Blood samples of these patients were drawn prior to the treatment, on 7 thand 30 thdays after the treatment. Results: The results indicated a positive relationship between 131I dose, CA and MN frequency. A statistically significant increase in CA and MN frequency in day 7 post- therapy and a decrease in mean levels of CA and MN on day 30 post-therapy were observed when compared to pre-therapy. Interpretation & conclusions: This study showed that the cytogenetic damage induced by 131I in low doses i.e., less than 555MBq was minimal and reversible. Patients can be motivated to undertake this safe and easy procedure as a first line of therapy in the treatment of hyperthyroidism.

Success rate of radioiodine treatment of hyperthyroidism in Qatari patients

To evaluate the response rate of hyperthyroidism to radioactive iodine treatment [RAI] and the mortality rate post RAI treatment in a Qatari cohort the records were analyzed retrospectively of 113 hyperthyroid Qatari patients [23 male, 90 female] treated with RAI [I-131] in the Endocrine Clinic, Hamad Medical Corporation, between 1984 and 2002. 90[79.6%] had diffuse goiter, 14[12.4%] multinodular goiter, 6 [5.3%] single nodular goiter amid 3 [2.7%] unknown etiology. Follow up ranged from two to ten years with free thyroxin and thyroid stimulating hormone being recorded at diagnosis; six months and one year post RAI treatment amid yearly thereafter. The incidence of hypothyroidism was 64.4% after six months post RAI treatment and 75.9% at one year. Euthyroid state was high in patients who did not receive antithyroid drugs, whereas the hypothyroid state was higher in a group with pre-treatment antithyroid medication [80% versus 62.8%]. The euthyroid state was more in diffuse hyperthyroidism 22.4%, while 84.6% of multinodular goiter became hypothyroid after six months of RAI treatment. Mortality rate was not increased post RAI treatment as compared to general population. Time incidence of hypothyroidism was 75.9% at one-year post RAI treatment amid time rate of hypothyroidism increased with the length of follow up to 10 years [86.7%]. There was no linear relation in response rate to increasing doses of RAI treatment groups

Avaliação da radioiodoterapia com doses fixas de 10 e 15 mCi em pacientes com doença de graves / Evaluation of radioiodine therapy with fixed doses of 10 and 15 mCi in patients with graves’ disease

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 por cento) foram submetidos a 10 mCi e 103 (62,8 por cento), 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 options for the hyperthyroidism of Graves’ disease are antithyroid drugs, surgery and radioiodine, none of which is considered ideal, as they do not act directly on the etiopathogenesis of the disease. Radioiodine has been increasingly used as the treatment of choice because it is a safe and definitive therapy whose administration is very easy. Some authors prefer to administer higher doses in order to deliberately induce hypothyroidism, while others recommend lower doses that result in a lower incidence of hypothyroidism and a greater incidence of euthyroidism. There is no consensus for the optimal regimen of fixed doses to be used and this is the main focus of the present study, where doses of 10 and 15 mCi of 131I were compared. Among the 164 patients analyzed, 61 (37.2 percent) were submitted to 10 mCi and 103 (62.8 percent) to 15 mCi. In the longitudinal analysis it was observed that remission of the hyperthyroidism was statistically different in the sixth month (p < 0.001), being higher in the group that used the dose of 15 mCi, but similar in both groups at 12 and 24 months. It may be concluded that the administration of fixed doses of 10 and 15 mCi of 131I brought about a similar remission of the hyperthyroidism after 12 months of treatment. Moreover, the remission rate of the hyperthyroidism had no association with age, sex or previous therapy with antithyroid drugs.

Efeito do propiltiouracil sobre a eficácia da dose terapêutica de iodo radioativo (I-131) no hipertiroidismo por doença de graves / The effect of propylthiouracil on the efficacy of radioiodine (I-131) therapy in gravesÆ hyperthyroidism / The effect of propylthiouracil on the efficacy of radioiodine (I-131) therapy in gravesÆ hyperthyroidism

Com objetivo de avaliar a influência das drogas antitiroidianas (AT) sobre a eficácia da dose terapêutica de iodo radioativo (DT), avaliamos retrospectivamente 226 prontuários de pacientes portadores de doença de Graves submetidos à DT no período entre 1990 e 2001: 58 pacientes sem antitiroidiano (AT), 119 em uso de propiltiouracil (PTU) e 49 em uso de metimazol (MMI). O estado funcional tiroidiano 9-12 meses pós-DT dividia os pacientes entre curados e não curados. Níveis elevados de T4 livre, captação de 131I em 24 h tiveram influência negativa sobre a taxa de cura, assim como menor dose de iodo administrada e maior volume do bócio (p< 0,05). O percentual de pacientes curados em uso de PTU previamente à DT foi de 70,2 por cento (84/119), enquanto nos pacientes em uso de MMI foi de 85,7 por cento (42/49), e de 84,5 por cento (49/58) nos pacientes sem AT pré-DT (p= 0,034). Em modelo de regressão multivariado, T4 livre > 4 ng/dl, maior volume do bócio, dose terapêutica < 10 mCi e o uso prévio de PTU tiveram relação com menores taxas de cura. Quando comparado ao grupo sem AT, concluímos que PTU implica em maior risco de falência pós-DT (OR= 3,13), o mesmo não ocorrendo com MMI (OR= 1,28).

Aiming at evaluating the effect of antithyroid drugs on the efficacy of radioiodine treatment (RAI) we retrospectively analyzed 226 patients with GravesÆ disease hyperthyroidism submitted to RAI between 1990 and 2001: 58 patients without any antithyroid drug (ATD) prior to RAI, 119 patients using propylthiouracil (PTU) and 49 patients using methimazole (MMI) prior to RAI. Clinical and laboratory parameters 1 year after RAI defined their clinical status (cured or not cured). High serum free T4 and 131-iodine uptake were negatively related with cure as well as lower RAI doses (mCi) and larger goiters (p< 0.05). The percentage of cured patients on PTU prior to RAI was 70.2 percent (84/119), while those on MMI was 85.7 percent (42/49), and 84.5 percent (49/58) of those without ATD prior to RAI (p= 0.034). On logistic regression analysis, free T4 > 4 ng/dl, large goiter, RAI dose < 10 mCi and PTU prior to RAI were related to lower cure rates. Compared to patients with no ATD prior to RAI, we concluded that the previous use of PTU implies in higher failure rates after RAI (OR= 3.13), an effect not observed in patients on MMI (OR= 1.28).

Permanent hypoparathyroidism following radioiodine treatment for hyperthyroidism.

Persistent hypoparathyroidism following 131I treatment is a rare but recognized complication. A case is presented, where a relatively small dose of 131I produced persistent hypocalcaemia.

Avaliação do tratamento definitivo do hipertireoidismo com radioiodo na Faculdade de Medicina do Triângulo Mineiro / Evaluation of radioiodine therapy as a definitive treatment for hyperthyroidism in the Triângulo Mineiro School of Medicine

O hipertireoidismo de origem auto-imune ou devido a doença autonômica da tireóide pode ser eficientemente controlado seja pela inibição temporária da hormoniogênese com as tiouréias, seja pela redução definitiva da massa folicular funcionante pela tireoidectomia ou administração de radioiodo. Com a intenção de conhecer os efeitos da radioiodoterapia na Faculdade de Medicina de Triângulo Mineiro, foram revisados 255 prontuários de pacientes com hipertireoidismo atendidos no ambulatório de tireóide entre janeiro de 1991 e 2001. O 1¹³¹ foi administrado a 61 pacientes portadores de doença de Basedow-Graves (DBG) (n=143), a seis com bócio multinodular tóxico (BMT) (n=17), e a 3 com bócio uninodular tóxico (BUI) (n=7). Apenas 1 caso de Hashitoxicese (n=40) de mais longa duração recebeu o mesmo tratamento. A maioria dos pacientes com DBG recebeu de 185 a 370MBq (5-10mCi) de 1¹³¹ e em dez pacientes com bócios volumosos foi necessário repetir a dose. Os pacientes com BMT e BUT receberam de 185 a 925MBg (5-25mCi) e uma segunda dose foi dada a três deles.Todos os pacientes foram curados do hipertireoidismo, não foram observadas complicações agudas, entretanto, o seguimento pós-dose até o momento detectou hipotireoidismo em 63% dos pacientes.

Hyperthyroidism either auto-immune or due to autonomic thyroid disease can be efficiently controlled by hormoniogenesis inhibition with antithyroid drugs or definitive reduction of functioning thyroid follicles number by either subtotal thyroidectomy or radioiodine administration. The effects of radioiodine therapy in the Triângulo Mineiro Medical School was investigated in 255 hyperthyroid patients treated between 1991 and 2001. 1¹³¹ was administered to 61 patients with Basedow-Graves disease (BGD), to six patients with multinodular toxic goiter (MTG), and to three patients with solitary toxic goiter (STG). Only one patient with Hashitoxicose ot unusual and longer duration received the same treatment. Patients with BGD were treated with 185 to 370MBq (5-10mCi) of 1¹³¹ but in ten of them with larger goiters it was necessary a second dose. Patients with MTG and STG received 185 to 925MBq (5-25mCi) and a second dose was given to three of them. All patients were considered cured from hyperthyroidism without acute complications, however follow up so far detected hypothyroidism in 63%.

Iodo radioativo no manejo do hipertireoidismo da doença de Graves / Radioactive iodine therapy in Graves' hyperthyroidism

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.

Terapêutica actínica do bócio multinodular precedida de dose única de hormônio estimulante da tireóide humano recombinante (rhTSH) / The actinic treatment of multinodular goiter preceeded by a single dose of recombinant human thyroid-stimulating hormone (rhTSH)

Bócios multinodulares podem causar sintomas compressivos e hipertireoidismo subclínico.O tratamento actínico é uma alternativa ao tratamento cirúrgico.Porém com TSH suprimido e captação baixa , a resposta ao tratamento é variável.Com o objetivo de elevar a captação e aumentar a eficácia do tratamento actínico foi utilizado TSH humano recombinante.Os trinta e quatro pacientes selecionados, com bócio / Multinodular goiters, often present pressure symptoms and subclinical hyperthyroidism. Actinic treatment has been alternatively used to surgical treatment, moreover suppresssed TSH and low radioiodine uptake, the response to I131 is variable To increase the goiter uptake of radioiodine, was used recombinant human thyroid stimulating hormone Thirty four patients presenting multinodular goiter...(

Minimizing radiation exposure from patients treated with lodine-131 for hyperthyroidism using a lead collar: a simple and effective approach

To construct a lead collar useful for shielding the electromagnetic radiation from the thyroid of patients treated with radioiodine 131I for hyperthyroidism, thereby reducing the radiation emitted from these patients. Materials and A specially designed cervical lead collar was used to shield radiation exposure from 'hot thyroids' of 20 patients treated with iodine-131 for hyperthyroidism. The collar was made of lead strips stacked together around a plastic neck support fastened around the patient's neck. Measurements of the radiation exposure rate were obtained at increasing distances from the patients [50, 100, 200 cm], with and without the lead collar, at various times after 131I treatment. Radiation exposure measurements over 3 weeks showed relatively high exposure rates in the first week after treatment. The radiation exposure from the patients wearing the lead collar was half that found in the same patients not wearing the collar. The use of the lead collar significantly reduced the radiation exposure of patients' surroundings. It was particularly useful in patients who could not abide strictly to the standard restrictive protocols after treatment with 131I

Early changes in thyroid-stimulating antibody activity following radio iodine therapy

The aim of this study was to determine whether or not the titre of thyroid-stimulating hormone receptor antibody with stimulating [TRAb-S] activity changes in patients with Graves' disease [GD] or toxic multinodular goitres [TMNG] 3 months after treatment with sodium iodide [131I]. Subjects and Serum specimens were obtained from 21 hyperthyroid patients [15 with GD and 6 with TMNG] at a median 0.5 months before and 3 months after 131I treatment using a standard ablative dose of 555 MBq. TRAb-S activity was measured in a sensitive and specific luminescent bioassay employing the lulu cell line and expressed as a stimulation index [SI; normal 1.5]. The mean TRAb-S in the GD patients was 2.72 SI [95% CI: 1.51-4.03] 0.5 months before administration of 131I and 3.98 SI [95% CI: 1.20-6.76] 3 months after administration of 131I. The difference was not statistically significant at p < 0.8. It was not elevated in the TMNG patients before [0.57 SI; 95% CI: 0.41- 0.73] and after [1.00 SI; 95% CI: 0.74-1.26] treatment either. Conclusions: Radioiodine therapy for GD or TMNG did not induce a significant change in TRAb-S activity at 3 months after treatment with 131I, probably due to effective antithyroid therapy or the timing of samples

optimal time of discontinuing methimzaole before radioiodine therapy

Hyperthyroidism is a common disease and one of the best methods for its treatment is radioiodine therapy. Treatment with antithyroid drugs brings patients to euthyroidism before radioiodine therapy. Antithyroid drugs should be discontinued before radioiodine therapy to increase thyroid uptake. The purpose of this study was to determine the optimal time of methimazole [MTZ] discontinuation. One hundred eighty four patients, who were referred for radioiodine therapy were classified in 3 groups according to the duration of MTZ discontinuation before thyroid uptake [RAIU] measurement. Group 1, 2 and 3 were patients who discontinued MTZ [48-72 hrs], [72-120 hrs] and more than 120 hrs before RAIU measurement, respectively. Mean thyroid uptake in group 1, 2 and 3 was [64 +/- 15.1%], [60.1 +/- 14.1%] and [59.3 +/- 12.8], respectively. No significant difference was noted in thyroid uptake between these groups [F=1.83, P<0.16]. This study shows that 48-72 hrs of MTZ discontinuation before radioiodine therapy is enough and longer term abstention is not associated with higher uptake

Evaluation of the effect of various parameters on the amount of radiation dose received by family members after 131-I therapy

The main concern with respect to discharge of patients from hospital after 131-I therapy is contamination of their surroundings and exposure of people who are in close contact with them. In this study, we evaluated absorbed dose received by homemates of these patients within one week of discharge from hospital. This study was based on 100 patients [23 patients with thyroid cancer together with 70 members of their families and 2 hyperthyroid patients plus 5 of their family members]. Measurements were performed by TLD. Patients were discharged from hospital if the dose rate from a meter distance of their thyroid was below 20 micro Sv/hr [ICRP-60]. The hospitalization period for those patients with thyroid cancer varied between 2-3 days [Depending on the amount of radioactivity received]. Hyperthyroid patients were treated as outpatients. Our data indicate that although hyperthyroid patients received much less activity in comparison to those with thyroid cancer, but due to the slow iodine discharge rate from their bodies, they radiated more to their surroundings. For patients with thyroid cancer, when the given activity increased from 100 mCi to 150 mCi, the average dose absorbed by their family members increased by a factor of 3. The duration of hospitalization as well as the amount of activity given to the patients have a significant effect on the amount of radiation dose received by the family members. In a group of patients who received 100 mCi of 131-I, the average radiation dose received by the family members of those patients who were hospitalized for 2 days were 1.5 times more than that of those patients who were hospitalized for 3 days, whereas following therapy with 150 mCi of 131-Iodine, the average radiation dose received by the family members of those patients who were hospitalized for 2 days were about 6.5 times more than that of those who were hospitalized for 3 days. The size of the patient's house and the time that family spends with the patient at house are other considerable factors. Our data show that by increasing the house size from 45-50 m to 75-100 m, the average radiation dose received by the family members reduce by a factor of 4, wheras by increasing the house size from 75-100 m to about 120-400 m, this dose only reduce by a factor of 1.5. The average dose for family members who were at house for less than 10 hours a day is about 5 times less than that of the individuals who were at house for more than 10 hours a day. In addition, average absorbed dose by children was about 9 times more than that of spouses. On the basis of this study findings, we suggest that parameters such as the amount of received activity, type of disease, house size, presence of children at house, duration of time which family members spend with the patient at house and differences in cultural behaviors between children and their parents should be considered in order to decrease the exposure of the family members and also to decide for duration of hospitalization and the approtiate time of discharge

Tratamiento con radioyodo del bocio difuso hipertiroídeo: influencia del pretratamiento con propiltiuracilo / Treatment of diffuse hyperthyroid goiter with radioiodine: influence of propylthiouracil pretreatment

Background: To stabilize Graves disease and deplete the preformed hormone, the use of antithyroid drugs prior 131I therapy has been suggested, specially in those patients with severe thyrotoxicosis and in the elderly. However, PTU may reduce the effectiveness of 131I. Aim: To study the effects of PTU pretreatment before 131I administration. Subjets and methods: A retrospective analysis of the medical records of patients with Graves disease treated with 131I from 1989 to 1997 was made. Of 244 patients with adequate follow-up for at least 12 months after 131I treatment, 142 had not been pretreated and 102 had received PTU prior to 131I therapy. Pretreated patients were distributed according to the number of days that PTU was discontinued before reciving 131I, forming four groups (a=5d, b=6-14 d, c=15-30 d and d=31-60 d). Radioiodine was delivered according to our protocol of 120 µCi per gram of thyroid tissue, as estimated by clinical examination. Therapy was considered successful when laboratory evidence of euthyroidism or hypothyroidism after one year of treatment was obtained and as a failure when undetectable TSH values persisted after 12 months of treatment with 131I. Results: All groups were comparable as to age, gender, goiter size, and 24 h radioiodine uptake. Control of hyperthyroidism was achieved in 76 percent of the non pretreated group. A similar percentage was observed in groups (b), (c) and (d). However, the disease was controlled in only 50 percent of group (a) patients (p <0.003). Conclusions: The therapeutic efficacy of 131I is significantly reduced when the PTU is stopped for only a few days prior to the use of radioiodine. We postulate that PTU has to be discontinued for at least 10 days before radioiodine administration

Tratamiento del hipertiroidismo con radioyodo: efecto de la dosis administrada sobre la función tiroidea y complicaciones asociadas / Treatment of hyperthyroidism with radioiodine: effects of administered dose on complications and thyroid function

Background: Radio-iodine is a definite therapy for Graves disease hyperthyroidism. However, the optimal dosage is still debatable. Aim: To assess the effects of different radioiodine doses on thyroid function and complications in patients with hyperthyroidism. Material and methods: A retrospective analysis of 139 patients with hyperthyroidism, treated with ratioiodine between 1988 and 1998. Radio iodine dose used was classified as low (<10 mCi), intermediate (10-14.9 mCi) or high (ü 15 mCi). Results: Thirty five patients were treated with low doses, 33 with intermediate doses and 71 with high doses. There were no differences between these patients in age, disease severity, frequency of post treatment euthyroidism or complications. Patients treated with low doses had a higher frequency of persistent hyperthyroidism than patients treated with high doses (25.7 and 4.2 percent respectively, p<0,001). Likewise, the frequency of subsequent hypothyroidism was 60 percent in patients treated with low doses and 84.5 percent of those with high doses, in whom it also appeared earlier. Associated complications were clinically irrelevant. In seven patients, Graves ophtalmopathy progressed after treatment, but this progression was not associated with the dose used. Conclusions: Radio iodine in high doses is useful, safe and effective for the treatment of Graves hyperthyroidism

Proposición de consenso para el uso de yodo 131 en el tratamiento de la tirotoxicosis y el cáncer del tiroides / Consensus proposal on the use of iodine-131 in hyperthyroidism and thyroid cancer

A consensus meeting held by the Chilean Endocrinological Society reached to 22 consensus proposals on the use of iodine-131 in hyperthyroidism and thyroid cancer, that are reported in this paper. Some of these propositions are: 1) Hyperthyroidism: A previous 131I uptake test must be performed. A calculated or an ablative dose should be administered. Hypothyroidism must be considered an objective rather than a complication. In patients with cardiovascular risk, normal thyroid function must be attained with propythioturacil. In cases of treatment failure, the dose should not be repeated before six months. It must be used with used with caution in children and teenagers. 2) Thyroid cancer: A iodine free diet is recommended prior to the therapeutic dose. A 100 mCi complementary ablative dose should be given after surgery, with a posterior exploration. This examination must not be done routinely, and if required, a 5 mCi dose should be used. For the treatment of metastases, a dose of 150 to 200 mCi is recommended. There is no radiation risk in hyperthyroidism or thyroid cancer. The only absolute contraindication is pregnancy. Recommendations for radiological protection are formulated. Hospitalization is suggested to protect other people from radiation exposure