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Antithyroid Drugs During Radioiodine Therapy

This study has been completed.
Information provided by:
Odense University Hospital Identifier:
First received: September 6, 2005
Last updated: February 2, 2006
Last verified: September 2005

Background: The use of radioactive iodine (131I) therapy as the definite cure of hyperthyroidism is widespread. According to a survey on the management of Graves’ disease, thirty per cent of physicians prefer to render their patients euthyroid by antithyroid drugs (ATD) prior to 131I therapy. This strategy is presumably chosen to avoid 131I induced ‘thyroid storm’, which, however, is rarely encountered. Several studies have consistently shown that patients who are treated with ATD prior to 131I therapy have an increased risk of treatment failure. Mostly, patients with Graves’ disease have been studied, while other studies were addressed also toxic nodular goiter. Thus, it is generally accepted that ATD have ‘radioprotective’ properties, although this view is almost exclusively based on retrospective data and is still under debate (13). Indeed, this dogma was recently challenged by two randomized trials in Graves’ disease, none of which showed such an adverse effect of methimazole pretreatment. It cannot be excluded that the earlier results may have been under influence of selection bias, a source of error almost unavoidable in retrospective studies. Whether ATD is radioprotective also when used in the post 131I period has also been debated. In the early period 131I therapy following a transient rise in the thyroid hormones is seen which may give rise to discomfort in some patients. The continuous use of ATD during 131I therapy leads to more stable levels of the thyroid hormones. By resuming ATD following 131I therapy, euthyroidism can usually be maintained until the destructive effect of 131I ensues. Nevertheless, many physicians prefer not to resume ATD, probably due to reports supporting that such a strategy reduces the cure rate. Parallel to the issue of ATD pretreatment, the evidence is based on retrospective studies and the ideal set-up should be reconsidered. To underscore the importance of performing randomized trials we showed recently that resumption of methimazole seven days after 131I therapy had no influence on the final outcome.

Aim: To clarify by a randomized trial whether continuous use of methimazole during radioiodine therapy influences the final outcome of this therapy, in a comparison with a regime in which methimazole as mono-therapy is discontinued 8 days before radioiodine.

Patients and Methods: 80 consecutive patients suffering from recurrent Graves’ disease or a toxic nodular goiter are included. All patients are rendered euthyroid by methimazole (MMI) and randomized either to stop MMI eight days before 131I or to continue MMI until four weeks after 131I. Calculation of the 131I activity (max. 600 MBq) includes an assessment of the 131I half-life and the thyroid volume. Patients are followed for one year with close monitoring of the thyroid function.

Condition Intervention Phase
Toxic Nodular Goitre
Graves Disease
Drug: Methimazole
Phase 4

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Open Label
Primary Purpose: Treatment
Official Title: The Influence of Continuous Treatment With Antithyroid Drugs on the Effect of Radioiodine in Patients With Hyperthyroidism

Resource links provided by NLM:

Further study details as provided by Odense University Hospital:

Primary Outcome Measures:
  • Thyroid function after one year of follow-up

Secondary Outcome Measures:
  • Thyroid radioiodine 131I uptake
  • Thyroid volume after one year of follow-up

Estimated Enrollment: 80
Study Start Date: January 2003
Estimated Study Completion Date: December 2004

Ages Eligible for Study:   18 Years to 85 Years   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Hyperthyroid patients going to be treated with radioiodine either due to recurrent Graves’ disease or toxic nodular goiter.

Exclusion Criteria:

  • Age < 18 yrs.
  • Allergy to anti-thyroid drugs
  • Substernal or large (> 100ml) goiter
  • Severe endocrine ophthalmopathy
  • Pregnancy or lactation
  • Suspicion of thyroid malignancy
  • Unsafe contraconception
  • Physical or mental condition that hinders corporation
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Please refer to this study by its identifier: NCT00150137

Department of Endocrinology, Odense University Hospital
Odense, Funen, Denmark, 5000
Sponsors and Collaborators
Odense University Hospital
Principal Investigator: Steen J Bonnema, MD, PhD Odense University Hospital
  More Information Identifier: NCT00150137     History of Changes
Other Study ID Numbers: 013
Study First Received: September 6, 2005
Last Updated: February 2, 2006

Keywords provided by Odense University Hospital:
Radioiodine therapy
Graves’ disease
toxic nodular goiter
antithyroid drugs

Additional relevant MeSH terms:
Graves Disease
Goiter, Nodular
Orbital Diseases
Eye Diseases
Thyroid Diseases
Endocrine System Diseases
Autoimmune Diseases
Immune System Diseases
Antithyroid Agents
Hormone Antagonists
Hormones, Hormone Substitutes, and Hormone Antagonists
Physiological Effects of Drugs processed this record on April 24, 2017