Alternating Hypothyroidism and Hyperthyroidism Complicated by Thyroid Eye Disease

This case study describes a 70-year-old woman with a history of primary hypothyroidism who experienced alternating hypothyroidism and hyperthyroidism, a rare condition thought to be mediated by changes in thyrotropin receptor autoantibodies. Initially diagnosed with hypothyroidism in 2004, she became hyperthyroid in 2018, which was managed by adjusting her thyroid medication. Her condition was complicated by thyroid eye disease (TED), leading to severe symptoms and requiring surgical intervention. The patient returned to a stable euthyroid state on levothyroxine by 2019, and her TED symptoms improved significantly. This case highlights the potential for autoimmune hypothyroidism to convert to hyperthyroidism and underscores the need for clinician awareness and further research into this phenomenon.