A 50-year-old female presents with fatigue, constipation, and weight gain. Her blood tests show a TSH of 10 mIU/L and a free T4 of 0.5 ng/dL. What could be the potential causes, and what are the next steps?
This patient's symptoms along with an elevated TSH and low free T4 suggest hypothyroidism. The next steps would include checking thyroid peroxidase antibodies to evaluate for possible autoimmune thyroiditis, and starting levothyroxine therapy to replace the deficient thyroid hormone.