Effective Iodide Therapy for Untreated Patients With Graves' Hyperthyroidism Avoiding Thionamide Drugs With Many Side Effects

Effectiveness of Classical Potassium Iodide Therapy for the Treatment of Untreated Patients With Graves' Hyperthyroidism, Avoiding Thionamide Drugs With Serious Side Effects of Agranulocytosis, Liver Injury, Vasculitis, Embryopathy or Frequent Side Effects of Skin Eruption

As the drug treatment of Graves' hyperthyroidism, Plummer reported the effectiveness of excess iodide in 1923 and iodide was used as the therapy for Graves' hyperthyroidism starting from the 1930s. After the introduction of more potent antithyroid drug, thionamide, most thyroidologists preferred to use thionamide expecting potent antithyroid effect, but some careful thyroidologists continued to prescribe iodide in mild type Graves' hyperthyroidism. Recently, American and Europe Thyroid Association recommended methylmercaptoimidazole (MMI), one of the potent thionamide drugs, as the first-choice drug for Graves' hyperthyroidism. However, it became apparent that thionamide has serious side effects such as not only agranulocytosis, but also severe liver injury, MPO-ANCA related vasculitis and embryopathy in the pregnant women. In Japan, one patient died of thionamide-induced agranulocytosis every year. The incidence of side effects including minor side effect of drug eruption is more than 10%. We used to treat the patients with Graves' hyperthyroidism with MMI, as we reported in J Clin Endocrinol Metab 65:719, 1987. However, many side effects of thionamide prompted us to revive the treatment with classical KI in our outpatient clinic and found that KI was effective in the patients who showed side effects to thionamide, resulting in remission (reported in J Clin Endocrinol Metab 99:3995, 2014). Therefore, we began to treat the patients without serious complications such as heart failure or arrhythmia, with 100mg KI since 1996 and followed for 180 days. We were surprised to find that serum thyroid hormone level decreased in all the patients. Thionamide drugs were added only when euthyroidism could not be achieved by KI alone. Compared with thionamide, side effect of KI was almost none. Between 1996 and 2004, about 504 patients were treated with KI and a third of the patients were successfully treated with KI alone and other patients were also successfully treated with the combination of KI and thionamide, suggesting additive effect, or by radioactive iodine therapy. The long term prognosis of the patients initially treated with KI was almost the same as the patients initially treated with MMI. Our clinical experience suggested that patients with Graves' hyperthyroidism are also susceptible to excess iodide, as in the cases with Hashimoto thyroiditis, and this suppressive effect of excess iodide on the thyroid gland is a useful information for many patients suffering from Graves' hyperthyroidism and thionamide side effects.

Study Overview

• Status: Completed
• Conditions: Graves Disease
• Intervention / Treatment: Drug: Potassium Iodide

• Study Type: Observational
• Enrollment (Actual): 504

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 15 years to 90 years (Child, Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Probability Sample

Study Population

primary care clinic

Description

Inclusion Criteria: Untreated Graves' hyperthyroidism. (elevated serum free T4 and/or free T3 level, suppressed serum TSH level, positive anti-TSH receoptor antibody and high thyroidal radioactive iodine uptake -

Exclusion Criteria: dropped out patients within 180 days

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Study Plan

How is the study designed?

Design Details

• Observational Models: Case-Only
• Time Perspectives: Retrospective

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Graves disease	Drug: Potassium Iodide

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Improvement of thyroid function	Normalization of serum free T4 level and TSH level during first 180 days on potassium iodide	180 days

Collaborators and Investigators

• Sponsor: Kyushu University

Study record dates

Study Major Dates

• Study Start (Actual): April 1, 1996
• Primary Completion (Actual): July 1, 2005

Study Registration Dates

• First Submitted: December 22, 2020
• First Submitted That Met QC Criteria: December 24, 2020
• First Posted (Actual): December 28, 2020

Study Record Updates

• Last Update Posted (Actual): December 28, 2020
• Last Update Submitted That Met QC Criteria: December 24, 2020
• Last Verified: December 1, 2020

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Immune System Diseases; Autoimmune Diseases; Eye Diseases; Endocrine System Diseases; Thyroid Diseases; Exophthalmos; Orbital Diseases; Goiter; Hyperthyroidism; Graves Disease
• Other Study ID Numbers: KyushuU Iodide 1

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No