An Open-Label, Single-Arm Study to Investigate the Efficacy and Safety of North Star Desiccated Porcine Thyroid Extract Tablets.

The North Star study is a multi-center, Phase 3, open-label, single-arm clinical study to evaluate the Efficacy and Safety of North Star therapy.

Inclusion Criteria: * Diagnosed with primary hypothyroidism, including Hashimoto's Thyroiditis, and on therapy with a stable dose of LT4 (minimum 50 mcg per day, administered 7 days per week) for at least 12 weeks prior to Screening * Have had euthyroid status for at least 6 weeks and up to 12 months prior to Screening (Visit 1), with at least one documented minimum stable dose of 50 mcg LT4. * Agree to practice a method of contraception * Female patients not pregnant or lactating at Screening * Agree to practice a method of contraception of greater than 90% reliability * Willing to give written informed consent for the Study * Provide written authorization for use and disclosure of protected health information Exclusion Criteria: * Any clinical condition or previous surgery that might affect the absorption, distribution, biotransformation or excretion of North Star * Hospitalization for a major illness within 5 weeks prior to Screening * Concomitant use of prohibited medications or supplements * Have uncontrolled diabetes * Taking or having taken prescription or over-the-counter weight loss medications within 6 weeks prior to Screening * Participated in another investigational new drug study within 30 days or 5 half-lives of the IMP, whichever is longer, prior to the first study drug administration. * For female subjects, be pregnant, nursing or planning to become pregnant during the study