Inclusion Criteria:

• Age 18-75
• Diagnosis of primary hypothyroidism for more than 12 months
• If they’ve had thyroidectomy for cancer, must be more than 5 years ago.
• Treatment of at least 25 mcg of synthetic T4 for at least 12 months (dose must be stable for at least 3 months)
• Documentation of in range TSH in the last year
• BMI 18-40

~1 year and 8 months