Graves' disease occurring after subacute thyroiditis: Report of a case and review of the literature

A 57-year-old woman with no previous personal or family history of thyroid disease developed typical subacute thyroiditis, with pain and tenderness in the anterior cervical region, fever, mild thyrotoxicosis; thyroid autoantibodies were negative, serum thyroglobulin (TG) levels were increased, radioactive iodine uptake (RAIU) values were decreased, urinary iodine excretion was normal, and erythrocyte sedimentation rate (ESR) elevated. Symptoms subsided with glucocorticoid treatment, with normalization of serum thyroid hormone and TG levels. Four months later, while still on a low dose of glucocorticoid, she had recurrence of hyperthyroidism, with no thyroid pain or tenderness, high RAIU values, positive thyroid-directed autoantibodies including TSH-receptor antibody. HLA typing showed positivity for B35 and DR3, suggesting a genetic susceptibility for both subacute thyroiditis and Graves' disease. The development of Graves' disease after subacute thyroiditis is extremely rare, suggesting that a genetic susceptibility to the disease must exist in such an instance.