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 causes hyperthyroidism, in a 62-year-old woman. After 20 years of hypothyroidism, the patient developed symptoms of hyperthyroidism, confirmed by lab tests showing elevated free T4 and undetectable TSH, along with positive TRAb antibodies indicative of Graves' disease. The transition is attributed to a shift from inhibitory to stimulating antibodies, suggesting that autoimmune hypothyroidism and hyperthyroidism may be part of a spectrum rather than separate conditions. The case underscores the complexity of autoimmune thyroid disorders and the potential for significant changes in thyroid function over time.