The See-Saw Theory: Hypothyroidism Due to Hashimoto's Thyroiditis Followed by Hyperthyroidism Due to Graves' Disease

This case report discusses a rare transformation from Hashimoto's thyroiditis, an autoimmune disorder causing hypothyroidism, to Graves' disease, which leads to hyperthyroidism, in a 62-year-old female patient. After 20 years of hypothyroidism due to Hashimoto's, the patient developed hyperthyroidism, confirmed by elevated free T4 and TRAb levels, after running out of levothyroxine. The report suggests that this transformation may be due to a shift from high inhibitory antibody levels to higher stimulating antibody levels, rather than gland recovery. This case supports the idea that autoimmune hypothyroidism and hyperthyroidism are part of the same spectrum, challenging the notion that they are distinct conditions.