Hemorrhage into a thyroid nodule as a cause of thyrotoxicosis.

Objective: To describe a case of thyrotoxicosis after nontraumatic hemorrhage into the thyroid gland during anticoagulant therapy. Methods: We report the details of the initial presentation, subsequent course, and outcome in a patient with a nontraumatic thyroid hematoma and thyrotoxicosis. Results: In a 63-year-old woman, an acute painful neck mass developed during follow-up while she was receiving low-molecular-weight heparin therapy for deep vein thrombosis. Ultrasound study and magnetic resonance imaging revealed a massive intrathyroidal hematoma. This finding was followed by an increase in serum free thyroxine and free triiodothyronine levels and a decrease in the level of serum thyroid-stimulating hormone (thyrotropin). Anticoagulant therapy was discontinued. The clinical course of the thyrotoxicosis was self-limited, and no antithyroid therapy was necessary. The serum thyroid hormone levels decreased into normal ranges as the hematoma underwent subtotal shrinkage. Conclusion: Endocrine glands are h...