Coexistence of adult-onset Still's disease and autoimmune hyperthyroidism in a patient who responded to corticosteroids and β-blocker.

The pathogenesis of adult-onset Still's disease (AOSD), which is currently thought to be an autoimmune disorder, may share similarities with autoimmune hyperthyroidism. This report describes a middle-aged woman in whom hyperthyroidism and Still's disease developed concurrently. During the course of her illness, the hyperthyroidism was observed to be aggravated whenever her AOSD was in the active stage. After her AOSD activity was controlled, her hyperthyroidism improved clinically. The extent of activation of her hyperthyroidism was observed in parallel to the extent of activation of her AOSD. Furthermore, the patient developed neutropenia after receiving either propylthiouracil (PTU) or methimazole, both of which are standard accepted medications for treatment of hyperthyroidism. Immune mechanisms contributed to PTU induced neutropenia have been proposed, and hyperthyroid patients treated with standard antithyroid agents should be monitored for blood cell counts especially for AOSD patients. Corticosteroid may effect Graves' disease activity, and steroids may play a role in the treatment of hyperthyroidism if a patient had drug allergies to antithyroid agents.