[Autoimmune thyroid disease: a case report].

Autoimmune thyroid disease is the most common cause of subclinical thyroid dysfunction (hypo and hyperthyroidism) in the western countries. Autoimmune thyroid diseases with clinical relevance (Graves' disease and autoimmune hypothyroidism) are common and can present with a large clinical and laboratorial spectrum. Hypo and hyperthyroidism can exist in the same patient, on different times. Progression from Graves hyperthyroidism to chronic autoimmune thyroiditis and hypothyroidism is now well-recognized and the inverse might also occur, although being rare. We describe a case report of Graves' disease in a patient with a chronic autoimmune hypothyroidism of long course (diagnosed 21 years ago).