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Block-replacement Therapy During Radioiodine Therapy

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00150124
Recruitment Status : Completed
First Posted : September 8, 2005
Last Update Posted : December 4, 2013
Information provided by (Responsible Party):
Steen Bonnema, Odense University Hospital

Brief Summary:

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. 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, possibly in combination with levothyroxine (BRT: block-replacement 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 BRT during radioiodine therapy of hyperthyroid patients 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: Consecutive patients suffering from recurrent Graves' disease (n=50) or a toxic nodular goiter (n=50) are included. All patients are rendered euthyroid by methimazole (MMI) and randomized either to stop MMI eight days before 131I or to be set on BRT. This latter medication continues until three months 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 or disease Intervention/treatment Phase
Toxic Nodular Goitre Graves' Disease Drug: MTZ+LT4 Drug: Methimazole Phase 4

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 100 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: The Influence of Continuous Block-replacement Therapy on the Effect of Radioiodine in Patients With Hyperthyroidism
Study Start Date : January 2003
Actual Primary Completion Date : December 2008
Actual Study Completion Date : March 2009

Resource links provided by the National Library of Medicine

Drug Information available for: Methimazole

Arm Intervention/treatment
Experimental: block-replacement therapy
BRT regimen until 3 months after 131I therapy
Drug: MTZ+LT4
Active Comparator: methimazole
methimazole stopped 8 days before 131I therapy
Drug: Methimazole

Primary Outcome Measures :
  1. Thyroid function after one year of follow-up [ Time Frame: one year ]

Secondary Outcome Measures :
  1. Thyroid radioiodine 131I uptake [ Time Frame: one month ]
  2. Thyroid volume after one year of follow-up [ Time Frame: one year ]

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 85 Years   (Adult, Older Adult)
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 contra-conception
  • Physical or mental condition that hinders corporation

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00150124

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Department of Endocrinology, Odense University Hospital
Odense, Funen, Denmark, 5000
Sponsors and Collaborators
Steen Bonnema
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Principal Investigator: Steen J. Bonnema, MD, PhD Odense University Hospital
Publications automatically indexed to this study by Identifier (NCT Number):
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Responsible Party: Steen Bonnema, Consultant, phd, DMSc, Odense University Hospital Identifier: NCT00150124    
Other Study ID Numbers: 012
First Posted: September 8, 2005    Key Record Dates
Last Update Posted: December 4, 2013
Last Verified: December 2013
Keywords provided by Steen Bonnema, Odense University Hospital:
Radioiodine therapy
Graves' disease
toxic nodular goiter
antithyroid drugs
Additional relevant MeSH terms:
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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