Inclusion Criteria:

We will enroll patients with AIT that meet all criteria 1 through 4 and then either criteria A or B as follows:

1. Are adults,
2. Have overt thyrotoxicosis (within 2 weeks prior to enrollment);
3. Are receiving medical therapy for AIT;
4. Are able to understand the study procedures and to comply with them for the entire length of the study.

and:

• A. have not normalized their thyroid levels after one month of standard therapy; or
• B. have persistent and clinically significant thyrotoxicosis (less than 25% decrease in T4 value or patients requiring hospitalization with CHF, tachyarrhythmias, hemodynamic instability or similar co-morbidities) after 2 weeks of standard therapy where additional medical therapy is deemed unlikely to be beneficial or with high risk of side-effects (e.g. hepatotoxicity of antithyroid medications, agranulocytosis of potassium perchlorate or ATD or fluid retention associated with steroids).

Exclusion Criteria: 

All candidates meeting any of the following exclusion criteria at baseline will be excluded from study participation:

1. Pregnancy;
2. Patients with prior neck surgery or neck radiation;
3. Patients with neck anatomy that precludes easy access by RFA to the entirety of thyroid parenchyma;
4. Patients on anticoagulation therapy;
5. Patients with comorbidities deemed too high of a risk for general anesthesia;
6. Treatment with another investigational drug or intervention (within 6 weeks of planned RFA);
7. Current drug or alcohol use or dependence that, in the opinion of the site investigator, would interfere with adherence to study requirements;
8. Inability or unwillingness of individual or legal guardian/representative to give written informed consent.