Metformin to Mitigate Sequelae of Radioactive Iodine Treatment for Thyroid Cancers

Inclusion Criteria: * Subjects with a diagnosis of differentiated thyroid cancer who have undergone total or near-total thyroidectomy and are candidates for iodine I-131 (I-131) treatment at Thomas Jefferson University Hospital (TJUH) are eligible to participate * Subjects must be diagnosed with differentiated thyroid cancer * Patients must have previously undergone or plan to undergo thyroidectomy; for those patients who have previously undergone surgery, pre-operative labs, including complete blood cell count with differential must be available * Patients who have a negative urine pregnancy test prior to enrollment. This should be done as part of pre-admission testing prior to surgery (within 14 days of study enrollment). * All subjects must be able to comprehend and sign a written informed consent document Exclusion Criteria: * Subjects who are pregnant or may become pregnant during metformin administration in accordance with radioactive iodine treatment guidelines * Subjects on metformin for any reason during the preceding 4 weeks * Diabetic subjects are eligible if they are not taking metformin, insulin or sulfonylureas * Subjects who have received iodinated contrast dye. Metformin treatment can be started the day after subjects complete iodinated contrast treatment. If a CT scan with contrast is scheduled after screening and consent, the metformin treatment should be stopped the day before iodinated contrast administration. Metformin can be resumed on the day after l…