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

Jarløv, A E; Hegedűs, László; Kristensen, Lars Østergaard; Nygaard, Birte; Hansen, Jens Munk

doi:10.1111/j.1365-2265.1995.tb02039.x

Cited by 140 publications

(114 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Even if we could determine the unknowns useful for calculating the individual dose more precisely, the exact delivered thyroid dose, although correlated to the therapeutic dose, was highly variable and was not statistically different between the three groups. Furthermore the increasing organ dose with the administered dose may explain, at least in part, the absence of predictability of an ablative dose (10), or the equivalence between a semiquantitative approach and a calculated radioiodine dose (11).…”

Section: Discussionmentioning

confidence: 99%

Optimized radioiodine therapy of Graves' disease: analysis of the delivered dose and of other possible factors affecting outcome

Catargi¹,

Leprat²,

Guyot

et al. 1999

Eur J Endocrinol

View full text Add to dashboard Cite

The best approach to radioiodine dose selection in the treatment of Graves' hyperthyroidism remains highly controversial. The formula to calculate the individual dose of 131 I to be delivered has been used for half a century and takes into account the thyroid mass, the effective half-life and the maximum uptake of 131 I. The objective of the present study was to evaluate the accuracy of this formula by determining the relationship between the administered dose of 131 I calculated to deliver a target dose of 50 Gy to the thyroid and the actual exact organ dose. We further analyzed if therapeutic success, defined by euthyroidism following the individually calculated dose, can be predicted by different pretreatment parameters and particularly by organ dose.One hundred patients with a first episode of Graves' disease and who had received optimal thyroid irradiation after precise dosimetry were retrospectively reviewed. The patients were categorized according to their thyroid function (plasma free thyroxine (T 4 ) serum concentration) as eu-, hyperor hypothyroid during and 1 year after treatment. The relationship between the administered dose and organ dose was assessed by simple regression. We compared free T 4 , free tri-iodothyronine, thyroid weight, the number of patients with antithyroperoxidase antibodies and TSH receptor autoantibodies, 24 h urinary iodine excretion, 131 I uptake, and the exact dose of 131 I delivered to the thyroid as pretreatment variables. Although we found a correlation between administered dose (mCi) and organ dose (Gy) (r = 0.3, P = 0.003), the mean coefficient of variation for organ dose was 45%. Individualized radioiodine therapy enabled euthyroidism in 26% of patients and failed in 74% of patients (33% had persistent or recurrent hyperthyroidism and 41% permanent hypothyroidism). 131 I uptake was significantly higher in the hyperthyroidism group in comparison with the euthyroid group. However, organ dose and other pretreatment variables did not differ among the three groups.In conclusion, these results confirm the low performance of individual dosimetry using what are established ratios, since the delivered dose to the gland, although correlated to the intended dose, is highly variable. The finding that other usual pretreatment variables are not different between groups, gives little hope for improving the way of calculating the ideal dose of radioiodine. We suggest to those not yet ready to give a standard or an ablative dose for Graves' hyperthyroidism that they abandon this way to calculate the 131 I dose.

show abstract

Section: Discussionmentioning

confidence: 99%

Optimized radioiodine therapy of Graves' disease: analysis of the delivered dose and of other possible factors affecting outcome

Catargi¹,

Leprat²,

Guyot

et al. 1999

Eur J Endocrinol

View full text Add to dashboard Cite

show abstract

“…Many dosage schedules of RAI, ranging from arbitrary deliberate ablation (5,6) to elaborately calculated doses based on the size of the thyroid gland, uptake of radioiodine or the turnover of radioiodine (2,6,7), have been used with little consensus about the most appropriate dosage regimen. Whilst it is possible to deliver a relatively accurate radiation dose to the thyroid gland, the biological response of the gland remains unpredictable.…”

Section: Introductionmentioning

confidence: 99%

Objective estimates of the probability of developing hypothyroidism following radioactive iodine treatment of thyrotoxicosis

Ahmad

Young

2002

European Journal of Endocrinology

View full text Add to dashboard Cite

Objective: Several risk factors have been shown individually to influence the outcome following radioactive iodine (RAI) therapy in the treatment of hyperthyroidism. However, no attempt has been made to determine their independent prognostic values that could be used in a regression model to provide objective estimates of the probability of developing hypothyroidism. Study design and methods: We audited records of all hyperthyroid patients treated with first dose RAI between 1980 and 1996. Patients were aetiologically categorized into Graves' disease, solitary toxic nodule and toxic multinodular goiter. Following RAI, outcome was categorized as hypothyroidism, euthyroidism and persistent hyperthyroidism. Multiple logistic regression analysis was used to identify significant risk factors, their prognostic values and probability estimates of developing hypothyroidism in the presence of one or more of these factors. Results: The cumulative incidence of hypothyroidism was 55.8% at 1 year and 86.1% at 10 years. Graves' disease (odds ratio: 4.29), presence of thyroid autoantibodies (odds ratio: 3.51), no antithyroid treatment given prior to RAI (odds ratio: 2.50), non-palpable goiter (odds ratio: 2.48) and high RAI dose (odds ratio: 1.90), were identified as significant independent risk factors. We then developed a predictive table that provides objective estimates of developing hypothyroidism. In the absence of all risk factors we can predict an 11.9% probability of developing hypothyroidism; this increases linearly to a 96.4% probability in the presence of all factors. Conclusions: These objective estimates would help in understanding the relative contributions of the known risk factors, and to predict the probability of developing hypothyroidism following RAI treatment. This would not only help patients make an informed consent for a treatment that would lead to life-long replacement therapy but may also prove useful in calculating the RAI dose that may reduce or delay the onset of developing hypothyroidism.

show abstract

“…Quatro estudos publicados na década de 90 mostraram uma taxa de cura variando de 59 a 100% (22,26,27,34).…”

Section: Discussionunclassified

“…A taxa de remissão do hipertireoidismo não parece diferir entre pacientes submetidos ao 131 I com doses fixas ou calculadas, de acordo com a captação do iodo e o tamanho da glân-dula (21,22). No Brasil, são utilizadas preferencialmente as doses fixas entre 10 e 15 mCi (23).…”

unclassified

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

Canadas

Vilar²,

Moura³

et al. 2007

Arq Bras Endocrinol Metab

View full text Add to dashboard Cite

RESUMOAs 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 131 I. 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 131 I were compared. Among the 164 patients analyzed, 61 (37.2%) were submitted to 10 mCi and 103 (62.8%) 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 131 I 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.

show abstract

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

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

Cited by 140 publications

References 18 publications

Optimized radioiodine therapy of Graves' disease: analysis of the delivered dose and of other possible factors affecting outcome

Optimized radioiodine therapy of Graves' disease: analysis of the delivered dose and of other possible factors affecting outcome

Objective estimates of the probability of developing hypothyroidism following radioactive iodine treatment of thyrotoxicosis

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

Contact Info

Product

Resources

About